I need some very detailed instructions on percussive slapping....

There's a discussion buried somewhere about LEFT HAND SLAP(ie, 'the fretting hand')-
...I usually post a Dave Larue link to a lesson from Bass Player mag(I'm not sure BP's site still has it, though they might...I'll check later when I have more time).
Getting both hands working together/against each other would be a start.
Learning the Clave & other assorted polyrhythmic figures would help(you can practice this without the bass in yer hands...you assign one rhythm to one hand & the other rhythm to the other hand; drummers & pianists do this all the time).
The concept is to produce counter or cross-rhythms...that's my .02 for now.

 

Im not very familiar with this double hand/ percussive slapping. Or, maybe I am and dont know it. Can you recommend any tunes that use it?

 

Here's the links(assuming they're still there)-

Left-Hand Slap
http://www.bassplayer.com/z1998/9809/larue.shtml

Slapping Across The Bar Line
http://www.bassplayer.com/z1998/9812/larue.shtml

Slapping In Groups Of Five-
http://www.bassplayer.com/z1998/9810/larue.shtml



...don't forget about Wooten's "Open Hammer Pluck" & the 'flam' technique(both are at Wooten's site).
I always mention learning the Clave(s) by tapping them out with both hands(on a desk, on yer gal's head, etc). Once that becomes familiar, you can transfer that bit of knowledge to the bass...something I'm still trying to absorb.
Later.