FreeBSD on Sun Ultra - installer on bootonly cd outputs weird display

[port at sigga.org]

I'm trying to install FreeBSD on a Sun Ultra 5, but I'm pretty new at this
stuff. I've managed to get the fbsd_bootonly CD to be the startup CD, and
it gives me 5 display options, like VT100, xterm emulator, FreeBSD
console, etc. However, every single one of these results in mangled
display (ie., characters appear on top of other characters - basically
what happens if one's emulation is set wrong) and an inability to use the
arrow keys, which seems necessary to use/configure the settings the
installer provides. I'm sure this is very simple to fix, but I have no
idea what to try. Thoughts?