Well, the processor in the 1400 is a PPC, but not a G3 if I remember correctly. Look in these threads for "unsupported" and you'll find links to the proper patches to get it installed on non-G3 hardware. You may or may not be able to get this to work. It really would be pointless to run OSX if you don't have enough physical RAM. I wouldn't try it with less than 128MB in OSX.
You can get the installer for Darwin and put the patches provided by Ryan Rempel of the infamous "unsupported" utilities to install on machines such as yours. Good luck! and post if you get this installed.