The keypad function allows to select a pattern on port 0, on which there should
be an interrupt, as well as to mask out those port pins that should not have an
influence on the keypad function.
That means
1) you can select for each port 0 pin whether it should be involved in
the keypad check or not, (mask)
and
2) if this port pin must be 0 or 1 (pattern)
In your case,
you would set the mask to: 1000:0111 to enable only P0.0..2,7
and the pattern to whatever might be applicable.

Now the pins P0.4,5 are still available for the comparator function.

I know I sound confusing, but the Datasheet or the Users Manual make this pretty clear.
I think they even contain a example for the comparator.
Cheers
Chris