I would use that points-based system, since I looked over it back when it was just a PrC creation system on ThirdEdition.Com, and I wish I knew of a way to truly make use of it. Unfortunately, it still has part of the same problem in the end: it's geared specifically towards the typical D&D campaign.
What I want is something a lot more futuristic, nigh on having mechas and the like, sorta like BattleTech or MechWarrior, but still have it in keeping with the D20 system. I don't have the D20 Star Wars RPG core book, so I can't really rely on looking at it... I'm basically looking at working the classes up from scratch. I'm gonna try to get the new Dungeon magazine tomorrow and get the D20 supplement for D20 Modern, but what I've been told has been that you see nothing really in the way of creating new classes. *sighs* Guess I'll just have to try and look at the DMG and wing it unless someone has a better suggestion.