You can install from a local fat partition if you put the plan9.iso file in the partition - don't unpack it, just put the single big file there and the installer scripts will allow you to chose it as a source for the full install.
A bigger problem is you have to boot the installer kernel, normally this comes from either a floppy disk or the install CDROM (which contains a floppy disk inage). If you don't have either of these you may be able to do some tricks by creating a bootable partition by hand on your hard disk, though this is going to get painful. Maybe somone else can think of some other technique. -Steve
