iScroll 2 is more for trackpads on older Aluminum PowerBooks that do not have the newer trackpad gestures. As such it's a kext that loads during boot. I use it on my 1.0Ghz PowerBook.
I use it to bring 3 finger tap Look Up to the Magic Mouse, as well as to change the behavior of the green button, on my Yosemite riMac. It's a useful app with support for many gestures.Ah... Oh well.
So this, from what I gather, is meant for pre-unibody nonmulti-touch trackpads? Like on a cMB for example, or an early MBP.
10.7, according to the download page. Too bad there isn't a version for PPC.Well, the current version of BetterTouchTool calls for 10.8 as a minimum I believe. So, take that as you will.