Yes. I personally have had pretty good luck with slime. I did slime a presta once, but I'm not a fan of removing the jam nut on the valve to do it. It was easier than I expected but could go horribly wrong.

*NOTE* I am not a fan of prestas. I usually drill my wheels for schraders if it can be done safely.

Also, I have a compressor, so once I've slimed the tube, I flush the stem with air before I reinstall the valve core.