answering my own question: I need to "man ifconfig" from my other machine, as EFW doesn't have a man page for ifconfig.
so, "ifconfig br0 192.168.0.1" worked beautifully. thanks to anyone who was going to help anyway!
nope, didn't actually work. ifconfig address 192.168.0.15 does change the interface address to that IP just for this boot. it otherwise boots up with the wrong/stupid IP assignation.
not even setting factory default from the console menu fixes it.
i ended up just reinstalling. but there's gotta be a better, easier way? damn you Linux!!! foiled again!