Well, it really all depends on what kind of water slide you want. There's 4 types:
-Continuous (What comes with RCT)
-Linear (Nonworking)
-Linear (Hacked, Working)
-Continuous (Hacked Realistic)
Of, these, I've done 3 out of the 4. I know how to do Continuous Realistic, but I've never actually attempted it. That one requires about the same amount of hacking skills as Linear hacked does. Basically, this is the most advanced hack that I do. It involves backwards track merging, 3 tracks, and invisibility. It took me hours to do the last one and I still don't know if I could do it again. But if you'd like those done in your park, I'll be glad to try. Contact me if you need that.
And Sands of Time is currently on hold as I'm entering New Element's Pro Tour and have started another park as well. Don't worry, I still have the desire for Sands of Time, just other things come first now.