Yeah, I'm still going to hold true to the XP/character level table. I'm just going to consider breaking the progression up into little pieces (this depends largely on how far my players are willing to go on this as well).
For example...
The character starts at level 1, and needs 1000 XP to reach 2nd level. This is 1 CR, thus 0.1 CR = 100 XP. If I break it up in feat-size bits, that'll be 200 XP a piece. They choose what ability they want to gain, and they 'train' in that while gaining XP (or they gain the XP, and choose where to put it in). Once they reach 1000 XP, they'll be level 2, and 0.1 CR would now cost 200 XP. The XP needed for one feat doubles to 400 XP. At level 3, it triples, etc...
If they want an ability that is greater than 1 feat (let's say 1.5 times as good; 300 XP for level 1), and they already have, say, 800 XP. They'd spend the normal amount for the first 2/3rd of the ability, and the level 2 amount after they gained 1000 XP. So, they first spent 200 XP on the ability. They become level 2, and for the last part of the ability they'll have to pay twice as much XP (200, for a total of 400 XP) to increase it further (and any other ability they'd want).
This way they wouldn't need to wait so long till they'd be able to gain something for their character (although it wouldn't be as much as they would get at a normal level up).
This would only be one way of doing it though. If the player wants, they can save up their XP to use for stuff like creating magical items, or to spend it all when they become level 2. It just depends on how much trouble the player is willing to go through, and what type of progression he/she feels comfortable with.
The end result should be the same either way (except if I missed something).
