After following the directions "set sw6.4 off, and the modify Linux Kernel Configuration I rebuilt the distribution ADI-2011R1-RC4_45 and installing the USB-LAN board I received the following messages with and without the extender board:
U-Boot 2011.09 (ADI-2011R1) (Dec 14 2011 - 13:56:11)
CPU: ADSP bf537-0.2 (Detected Rev: 0.2) (bypass boot)
Board: ADI BF537 stamp board
Clock: VCO: 500 MHz, Core: 500 MHz, System: 125 MHz
RAM: 64 MiB
Flash: 4 MiB
KGDB: [on serial] ready
Net: bfin_macWarning: failed to set MAC address
Hit any key to stop autoboot: 0
*** ERROR: `ethaddr' not set
Wrong Image Format for bootm command
ERROR: can't get kernel image!
If I set the switch sw6.4 on, then I can boot normally, but the extender ports (ethernet or USB) do not appear in ifconfig...