????? The alignment specs are no longer possible? What does that mean? They should be possible unless his car was lowered a whole hell of lot.
I'm not going to stick my nose any further into something I don't completely understand, but will make a couple suggestions. Do a search and read. Start with this:
http://forums.pelicanparts.com/porsche-911-technical-forum/614969-chime-my-alignment-specs.html.
You're right in that your settings will have changed due to the lowering and that getting them set correctly now is important. Your requirements will vary depending on what kind of driving you do. Cruising, puttering around town, spirited drives in the country or general stuff most people do, and the factory specs should be fine. Autocross or DEs will impose different requirements.
If you want the factory alignment specs, I see no reason you can't do it. My car is significantly lowered, and my alignment isn't that much off factory. It's a bit more aggressive, but I don't do a lot of track driving with it, either.