Hi,
I think you can probably use any of the 08M2 pins, except the serial I/O (c.5 and c.0). But the PE should flag an error if you try to program any that aren't suitable. I've certainly used an interrupt with an 08M2, but can't remember the pin (probably HSERIN).
The 08M2 is not one of the exceptions in the "Applies to: (all)" section at the foot of the command page, and the other M2s listed are in the "Restrictions" section. I think the restrictions apply to the 14/20M2 because their "silicon" (chip hardware) has the pins grouped as three (partial) ports and the code wants to test only one (port C). All the 08M2 pins are on a single port, which actually may be named either B or C.
Cheers, Alan.