Is it possible to use the 16F627A's on board comparator to call a subroutine?

I would like to compare a voltage (that ranges from 3 to 0 VDC relative to ground) to the internal voltage reference set to 0.5V. If the input voltage is greater than 0.5V, I want a subroutine to be called.

I read the datasheet, but that just made me more confused. Couldn't find any good examples on how to use the comparator with Pic Basic.

So, what I need help with is:
1. How do I set the internal voltage reference to 0.5V with PBP?
2. How do I setup the PIC to get the voltage in with PBP?
3. How do I use the VRCON register to call a subroutine with PBP?

The PIC doesn't need to do anything if the input voltage is below 0.5V.

Any help is appreciated!