Well I would use the mage Advanced class straight out of the D20 modern book.
The adept... well im not sure how you could do that, perhaps the martial artist out of the Modern Players Companion.
You could try the force adept class out of StarWars D20, and failing that (or if you have no access to it) the best I can suggest is to make your own advanced class or remove it all together.
The magic and adept wont be the same, thats just something you're going to have to accept. Not unless you use extensive amounts of house rules...
Or
You could use the mage Advanced class and rule that each spell slot is worth its level * 5 in spell points (0 level costing 1 point). Every time the mage casts a spell he must spend spell level*5 spell points and make a fortitude save dc 10+ spell level. If he fails he becomes fatigued but casts the spell. he fails again hes exauhsted, fails a third time hes unconcious.
you might even be able to remove the spell slots entirely, mages have a fairly weak fortitude save. That system should knock them out cold fairly effectivly if they cast too much. (Thats a combination of a dragonlance variant rule and a spell point system I use in a game i run... I haven't had much trouble with the spell points so far, mages dont seem to overpowered with it. Actualy I found it kinda evens them up a little when compared to fighters)
Thats a standard arcane mage tho, the shamans and adepts will be a little more difficult to emulate (Id suggest custom made classes)
