Yea, I'd have to agree with Jeff on that. I'm confident with aggressive stripper on clocks like the Garcon, but I've never used it on plastic. It might do just fine, but before using it on a good clock, I'd try it on some scrap clock first. I'm not sure how the plastic would react to a harsh chemical. The last thing you would want is for a section of the clock to warp or something.
Like Jeff said, a nice, gentle solvent would probably be your safest bet, but avoid any type of abrasive when removing the paint. It would be a shame to get all the paint off and then find out you scratched the plastic beyond repair. Frankly, I wouldn't trust anything more than one of those sponge-type pot scrubbers or paper towel. If the paint is loose enough, it should come off without very much effort.