Vista, Functions and Parameters of pcalua.exe

I know it's a bit late to respond but...
pcalua.exe is created when there's a compatibility issue with a program. The first time the problematic program is launched, a compatibility assistant appears and then "sets" the program's compatibility settings. The next time this program is launched, it will run in compatibility mode.
That's when pcalua.exe comes into play. The compatibility assistant creates the scheduled task pcalua.exe the first time: it will run every time the problematic program is called. This prevents the compatibility assistant from restarting every time.
As for what the switches mean, well... -_-'