Gday Goldfox and welcome..

Not too sure if this will be of any use to you, but here's a way you may find usefull..

I've just read your post and had a try at seperating the skin from the rig. It's a bit of a cheat, but what you can do is duplicate the skin when it's in the desired pose, before unlocking its Translate, Rotate and Scale channels. After the channels are unlocked, you can move this new geometry around as you see fit.

The problem I can forsee is that all the models will have different names, and may need a bit more work to put all theses 'different' models together into one animation. I guess you could just export the pose concerned at each phase before then going back in and renaming them.

So, to sum it all up, here's what I did.

1) Set the pose wanted
2) Select the skin and hit Shift-D (duplicate)
3) Highlight the Names of the greyed out attributes in the channel box (all the rotates, scales and translates)
4) Hold right mouse button and select Unlock Selected
5) Move object off to the side and return to step 1 untill all poses are complete.

I know nothing of exporting ready for game engines, so I'm sorry, but I can offer no further advice.

Anyway, here's a pic of what I was able to achieve. It took about 2 minutes btw. Note only the hand on the right has a rig and that the other 3 are copies made using the method outlined above.
Simon.