Aight, so... Chill to BRP.
In Chill (Keep in mind it's the Mayfair version), stats are rated for humans from 10 to 90, with inhuman monsters able to exceed that threshold. Divide by 5 and you have a range of 2-18, which is close enough to BRP's 3-18 starting range for characteristics. Bam. Easy.
Skills... well, both games use a percentile-based skill system, so just use BRP's system in place of Chill's. If there's a skill from Chill you just gots to have, we'll negotiated.
The Art- The Disciplines are essentially learned as skills. They're percentile-based, much like BRP spells, so that's pretty straightforward. I could give PCs a small pool to purchase Disciplines, much like OpenQuest's basic character generation, with the option to cash those in for extra combat skills/regular skills if you want to play a character who doesn't use the Art, or to cash in combat/useful skills for more Art points.
The one snag I run into here is that, in Chill, the skill system distinguishes if a character is Student, Teacher, or Master level in a particular skill. This distinction is purchased aside from the character's actual percentage in the skill. Applied specifically to the Art, a character's proficiency level often affects the potency of the Discipline. I could either assign a proficiency level to a given percentage (Maybe up to 50 you're a student, 60-90 you're a Teacher, 91+ you're a Master)
Disciplines of the Evil Way can be a little more fast and loose, since PCs can use them anyway. (Unless I decide to go full-on Beast Within, but that's an entirely different can of worms I'm not keen on opening yet.)
This is probably about as deep as I want to go. No game system converts perfectly; the idea is to keep the concepts instead of point-for-point, level-for-level. Hell, I'm not even running the (admittedly) bare-bones setting of Chill anyway. I think this game is simply going to be "Chill-esque" in terms of attitude and presentation. I'll probably keep SAVE, RAX, and the Unknown, or at least their near-equivalents, but I'd like there to be more factions than just The Totally Good Guys and the Totally Bad Guys.