amd64 6-release cd install, no serial console joy

Trying to install amd64 6.0 release on some Dells, PE850 and PE2850. 
BIOS all setup same as what works just fine with 5.4 (both i386 and
amd64 cds).  boot -h appears to work until it gets to the loader and
the console output goes to video.  No keyboards or monitors plugged
in, just a serial console server.  Have tried variations on serial
redirect in the BIOS but nothing seems to work.

Anyone else have success or no with serial console redirect on amd64 6.0 cd?

regards,
-Jan