Nut raisers are great but make fretting impossible. I like to set guitars up specifically for slide so I can fret lower down but still slide without buzzing. Nut raisers are more for the dobro experience where you learn everything by the slide or tone bar but they are also good just to have a try with your normal guitar.
But if you really want to get into electric slide I think you need to go with a heavy action and strings, it's much more versatile unless you plan on slanting the slide/tonebar which is really a whole different way of playing.
Or just raise your action for a few days, count the turns on each saddle, note them and go back when you have had enough, that's what I do :)