no tuts I know of specifically for the IPO editor (not saying there aren’t any).
I’m not sure that the whole animation needs to be sped up so much as the hitting the ground motion needs to be made less “soft.” A ball isn’t going to slow down before hitting the ground. It will slow down when reaching the apex of its bounce.
why don’t you try this though.
split the view so that the 3d view takes about 2/3 of the screen and the IPO window the other 1/3. trying to switch between the two gets to be a pain really fast and you don’t need more than 1/3 of the screen for the editor usually.
On the header, there should be a pull-up window with the IPO types. make sure this is set the Object. The curves with keyframes should have colored boxes next to them on the right bar.
You’re going to want to edit the IPO “control points” so select the ball and go to the editor. find the relevant curves (LocZ in this case), select them, and press tab to acces the control points. IPO curves act pretty much like bezier curves, with handles and such.
go to the keyframe where the ball hits the ground, there should be a coresponding handle on the curve. You want to make the curve steeper where it hits the ground. You can either make the handle a vector handle (Vkey), or make it a free handle (Hkey I think) and manually move the handle edges). This will make the hit and rebound motion faster.
you can do the opposite thing to the “hold” at the top of the bounce if want as well, though you may not need to.
that should be enough to get started with the IPO editor (if my directions were unclear, just tell me)
for squash and stretch, there should be a bunch of tutorials if you search, either here or on google.