How hard would it be to modify a template?

[Ualaa]

Essentially, one of my players wants to add one or more templates to his character, which are worth CR+1 or CR+2, depending on the template.

If I compare a Fighter 4, to a Fighter 3 (with a CR +1 template), they have the same CR value.

I would like the template to be worth (cost) as many levels as the CR adjustment.

Ideally, it would count as a level taken, but not grant BAB, Saves, Hit Dice or Skills.

But feats would still be attained at the correct levels.


Something like:
01. Advanced Creature.... Feat.LV.1
02. Druid 01..................
03. Druid 02.................. Feat.LV.3
04. Rogue 01.................
05. Rogue 02................. Feat.LV.5