answering the how to fix the interior door question myself!
ok... for anyone who has gotten so far as to get the door panel off, but then been flummoxed as to how to continue to replace the door handle (with only two screws... so really... how hard can it be?) let me tell you this:
first... anyone with a screwdriver and some patience and some care can do this job.
1. if you are wondering if you have to take apart the entire door, the answer is: NO! you will need to peel back the plastic from the upper left corner of the door (upper right if you're working on the right side of the car.)
2. presumably, at this point, you've also unscrewed the (mere) two screws holding your broken handle in place. (if not, now would be a good time.) you can peer into the top of the door w/a flashlight, or into the holes in the door you've exposed by peeling (carefully) away the plastic to get a glimpse of what the interior looks like. you will see that there is a thick wire hook going through the back of the handle, which is holding it in place (and which also provides the leverage to unlatch the door, when everything is working right.)
3. looking down through top of the door for some visual guidance, rotate the handle about 180 degrees to the left (right on the right hand side of the car, right?) to get it off the hook. once freed, you can slide the handle through its handle slot in the door to remove it.
4. if you don't have a gasket (foam thing-y) on your replacement handle, re-use the one from your broken handle, if you can. just place it around the edge of the handle.
5. slide your new handle into the handle slot. (hold onto it... imagine it would be a real hassle to drop it into the door.) looking down through the top of the door -- or really however you can sort of see anything to grasp what's going on -- with your left hand maneuver the thick wire with the hook so it slides into the hole on the handle (you will probably need to move it away from the interior side of the door) and slowly rotate the handle on the hook about 180 degrees until it's facing the right way in the handle slot. screw in the two screws. (this is probably a good time to shut the door and try our your handle) replace the interior panel. voila! have a beer and enjoy your handiwork. ;-)
(there are plenty of posts that deal w/the intricacies of getting off the door panel -- it's in most of the bmw repair books, too... so i'm not going to deal with that.)
i dunno why no one's given directions for this before. maybe it's too easy of a task. if anyone wants to edit the instructions -- because maybe they're not clear, please feel free.