I work part time and have done so for a number of years. I was with my previous employer for nearly 7 years, and 3 of those were part time and I have been in present position for about 18 months.
In my experience positions for generalists are harder to find in a part time capacity than specialist roles.
Having said that though, in my opinion the generalist positions you might find are more likely to be p/t HRM's in smaller organisations. Not a bad thing necessarily , just depends what you are after. If you are looking for larger organisation as part of a team, part time might be harder to find.