My own MT is pretty much like yours, Psion, except that I give nothing else than spellcasting levels...
BAB: puny
Saves: fort puny, ref puny, will puny (unless the stacking of +2s from first levels change with 3.5, in this case, good Will save).
Spellcasting:
1 +1 arcane spellcaster level, +1 divine spellcaster level
2 +1 arcane spellcaster level, +1 divine spellcaster level
3 +1 arcane spellcaster level, +1 divine spellcaster level
4 nothing, ahahah
5 +1 arcane spellcaster level, +1 divine spellcaster level
6 +1 arcane spellcaster level, +1 divine spellcaster level
7 +1 arcane spellcaster level, +1 divine spellcaster level
8 nothing, ahahah
9 +1 arcane spellcaster level, +1 divine spellcaster level
10 +1 arcane spellcaster level, +1 divine spellcaster level
On the other hand, I would add Use Magic Device on their skill list. Ehehe, they would nearly never nead it anyway.