Hi,
CMxCON looks fine to me, bit 7 = 0 which means the comparator is disabled (which it is by default on this device so no real need to add that but can't hurt).
ANSEL sets RA1 and RA2 to analog, I suppose that's what you want.
ADCON0 looks fine except possibly for bit 7 (I can NEVER remember when to use which setting). It should be in one state when using 8 bits and the other when usign 10 bits.
ADCON1 sets the ADC clock to FOsc/64 which makes it run REALLY slow if the oscillator is 4MHz, try the RC mode instead.

I checked the manual, if not told otherwise SHIFTOUT sends 8 bits even if the variable is of another size. You have mode 1 selected (MSB first) so my question then is if it shifts out the high byte of your word, MSB first or the low byte of your word, MSB first?

I don't know, perhaps you've already done this, but I would make sure I had full control over that pot-chip first and THEN focus on the ADC.

/Henrik.