[areteas]

I don't do psionics, so I'm afraid I don't have the sourcebook you're working from... but it sounds like these three path skills are fairly static? There are ways to alter the restriction expression via eval script if necessary, but this way's a bit simpler.

If it was (for example), a choice of Stealth, Bluff or Diplomacy, you could set up the class special along these lines (cribbed from any of the 'and one of these skills is always a class skill for you' traits):
Item Selection section
Select from... none.
Custom Expression: thingid.skDiplo|thingid.skBluff | thingid.skStealth

Then an eval script (say post-levels 10000) to set the bonus (assuming an untyped bonus here, adjust as necessary to whatever the sourcebook/ uses as the bonus type):

~ If we're disabled, do nothing
doneif (tagis[Helper.SpcDisable] <> 0)

if (field[usrChosen1].ischosen <> 0) then
  field[usrChosen1].chosen.field[Bonus].value += 2
  endif

~ Set shortname as appropriate
field[shortname].text = "Warrior Path: " & field[usrChosen1].chosen.field[name].text

If the three skills to choose from depend on some other ability or variable, there're ways to set that up too.