after 2 days of trial and error, i figured out a way to do it.

http://necros.quaddicted.com/temp/hunterq1.jpg
(hunter was always my favourite ^_^ )

the process is roundabout and exceedingly headache inducing. :P
also, if you want to do this, read my whole post first.

step 1: we need to get the 3 q3 md3 files (head, torso and legs) into 3ds max (in my case).
for this, i used this script: http://www.scriptspot.com/3ds-max/quake-iii-md3-importer-public-beta
surprisingly, it worked in 3ds max 9 (usually most scripts this old would never have worked).

if you follow the instructions on that web page, it will work properly: use the script to import upper.md3 first, then lower, then head. this will make sure the tags link up with the body parts.

(pre) step 2: involved transfering the animation key frames from the torso tag onto the torso mesh itself.
the torso doesn't actually move, it only has vertex animation; it uses the tag to make sure the torso is properly oriented with the legs but in order to export the animation, both the translation and rotation must be on the torso mesh object.

step 2: select your torso tag and go to file -> save animation.
save the file with a name of your choosing some place convenient.
now, select your torso mesh and unbind the mesh from the tag.
go to file -> load animation and select the file you saved earlier.
you will get a message box "No tracks are mapped. Create map file?" and click yes.
you'll see 3 list boxes, two on the sides with the middle one empty. Ctrl+Click on both the sides the item that says "Exposed World Transform" then click the button with the arrow "<-"
this tells max to use the world transform from the save file on the selected object. Click the "save mapping" button on the bottom and save it somewhere (not really important, it just doesn't let you load the animation without saving first) then click "load motion".
if everything was successful, your torso should now be moving on it's own, without being linked to the torso tag.

step 3: redo step2 except for the head.

step 4: now you need to rearrange the uv mapping. originally, head textures take up the same spot on uv maps as the body does, but when you are combining all of this into 1 model, you will have overlapping uvs for the head on the body area.
for a quake3 player model, the body is 256x256 and the head (in the case of hunter) comprised of 2 128x128 textures (the face + the feather hat).
i chose to make a 512x256 texture, with the body on the left, and the face+hat stacked on top of each other right next to the body. this leaves a 128x256 empty area we can use for the weapon.

step 5: before we can export, there is one final step to do. the thing that drove me crazy for the longest time was that the head would never export any frames, even though it had keyframes.
the problem is that the tool i had to use to convert the 3ds max models back to md3s (http://www.quakeunity.com/file=481) only looks at *vertex* animation when deciding if there's a key frame there or not. so what you need to do is go into the head at vertex sub-object level and add a key frame to any 1 vertex at the end of the animation. (i just move a vertex an incredibly small amount).

step 6: delete all the tags (they aren't needed) and export the whole model as an ase file. make sure you have it set to export keyframes every frame.

step 7: open up npherno's md3 compiler (http://www.quakeunity.com/file=481). import the ase file but only select 1 component. export the single component back into md3. close, reopen the program and do the same for the torso and head.

step 8: use preach's md3tomdl converter (http://www.btinternet.com/~chapterhonour/md3tomdl.zip) to convert the 3 pieces into mdls.

step 9: (these next steps are the 'dumb' parts) open qme and open up the legs. then, using import object, import the torso.
qme, annoyingly, has no options with what to do with incoming object's skin mapping, so although the nice uvw maps were preserved from the original md3 files, they will be placed next to each other. 

step 10: open quark 4.07 (yes, really). load your combined model. you'll notice your actual skin now is absolutely massive (i think it was 1536x256) because qme just kept adding stuff on the sides.
what you need to do in quark 4.07 is select the torso verts on the skin mapping editing window and slide them way over to the left (where the legs verts are).
for the head verts, i wasn't able to slide them over next to the body verts because they were considered 'on the other side' and so werent' allowed past the mid-point of the skinmap.
so i slide them just to the right of the mid-point.
finally, (still in quark) go into the edit -> model properties menu. change the width to 512 (make sure the 'right' radio button is selected so it will remove stuff from the right side, not the left).
this should place the head verts right next to the body verts and everything should be perfect. if not, the gods have not smiled uopn you and you are SOL, sorry.
Save.

step 11: now all that's left to do is to name your frames which you can do easily in qme.

yay, you have a q3 player model in quake with uvw and animations preserved. :P

note 1: i'm not sure if you could skip the 3dsmax process for the legs and torso, since the only real modification we had to do was with the head (regarding the uv mapping change).

note 2: there may be a way to collapse all 3 components into a single mesh object. the problem is that simply attaching the mesh objects together discards their vertex animation with no way of reclaiming them.
the other method involves using boolean with unify operations but you can't export frames that way because the key frames of the boolean operands don't count and the md3 compiler will only see 1 or 2 frames. (although this method does at least preserve the vertex animation)


so yeah, anyway, in most ways, it's probably better to do it the way you did madfox, import a single frame, combine it all into a single mesh, re-weight the vertices with new bones and animate it again yourself. this is the more logical way, i suppose, but i really wanted the original animations as well. :P 

npherno's md3 compiler: http://www.quakeunity.com/file=481

preach's md3tomdl: http://www.btinternet.com/~chapterhonour/md3tomdl.zip