Evasion and Improved Evasion...
Perhaps require the Soulknife to be psionically focused to use them? Also, maybe start with only Evasion only working in light or no armor (like a rogue), then gain compatibility with medium armor around level 6 or so?
Would gaining access to ninja ki
tricks be a viable option? I'm not sure which is better for the SK: spending PPs in place of ki
, or expending his focus. (If you don't already have it, Super Genius' OGL Power of the Ninja
has some really neat ninja tricks in it.)