I think this was covered on another thread and the conclusion was it would be very tricky as the curve of a snooker pocket actually starts before the cut of a typical pool pocket, hence you'd be inserting something larger than the pocket itself, which wouldn't work.
That said there are some companies that do interchangeable cushions & pockets together.
If you're trying to convert your table to something like Chinese 8-ball....
...you'll need a whole new set of rails.
Snooker rubber has a flat edge...pool rubber is vee-shaped.