re: Bug#492878: lenny installer -dosen't detect Broadcom ethernet adapter
I think this was fixed very recently, if you look back at the traffic
The installer should at least prompted you to supply a .fw firmware file.
Did it do this?
The firmware can be obtained from the firmware-* packages, e.g.
See also these bugs for a bit more background.
If this isn't fixed for you in a recent daily image could you explain more
about your hardware (e.g. lspci -knn output).