I don't remember the particulars, but I do remember I had some trouble installing/booting osx on a beige g3 when the boot disks were not the master drive. To make it easier on yourself put the dvd on one and the hd on the other ATA bus. I also recommend Tiger over Panther. It runs faster and you can keep itunes and firefox up to date. I also setup a swap partition at 2-3x my memory and move the swapfiles there. (It appears to help, but I have no empirical data.) Search for "osx moving swap files" for more info. Also get yourself a copy of TinkerTool and switch off dashboard, as it sucks up more power that it is worth on a g3.
JHV