Thanks johns, I'll check the ride heights before I get it aligned. It's a real pain for me, the only Porsche shops around here are two hours away in Wichita, so it's a little bit of a road trip to get anything done. I don't think I could own this car if I didn't DIY.

Start bysetting tire pressure , then measure from the wheel lip to ground I believe the rears normally measure about 1/2 less than the fronts. If the wheel well heights are off by a lot then setting and more accurate measurement is done measured to the ends of the torsion bars.
I expect most tire shops can do an alignment you don,t need a Porsche specific shop They often don,t know about all the different adjustments available but if your heights are close to start with(1/4 side to side or less) they should have a straight foreward alignment job.
Your original post indicates a problem I think is caused by toe out only If you are going to get it professionally aligned check wheelwell heights first .You can alter the toe yourself with a tape measure in the driveway.Long life for tires and best results will come from accurate equipment.

matt,

since it is so incovenient for you to take your car somewhere for alignment why not try at home?

i had similar issues to you. i also had severe inside tyre wear - common on 911's i was told.

i looked at the fronts (with my dad) before we checked the alignment and both agreed that the car had severe toe out. this was mostly by looking down from above each fender.

how wrong we were. there was over 1/2" of toe IN!!

its very easy to check - even if until you get it done professionally. but i had great results and the car tracks very well - no pulling. i have about 1/16" toe in now.

try here http://forums.pelicanparts.com/showthread.php?s=&threadid=108288&highlight=settin g+toe