What Les said...Ivan Law's book is the place to start if you want to learn about cutting gears.
If you want to do it all in the lathe, you'll need a milling attachment and some kind of indexing attachment. Straight cut (spur) gears are pretty easy. Bevel gears are possible...at least in one form. You can't reasonably do the tooth form that's found on commercially-made hobbed bevel gears, but you can do a tooth form that works, which is explained in Ivan Law's book.
Another source of information about cutting bevel gears in the home shop is Kozo Hiraoka's book "Building the Heisler" (or maybe it's in "Building the Shay," or maybe it's in both). Kozo writes the clearest construction instructions of anybody I've ever read. The books are available from Village Press.
[This message has been edited by SGW (edited 04-18-2005).]
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