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!
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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!