Hi,
At the moment I haven't build yet the serial mod since this week my electronic shop is closed, so I haven't a serial console yet.
I had to build the "two week ago release" since yesterday one was broken.
I can tell you that the firmware build successfully, by only changing brcm-2.4 to brcm-2.6, and no other changes. I uploaded it using tftp (with the same method I used to upload witerussian openwrt-wrt54g-squashfs.bin).
After upload, dmz led start blinking, after 10 minutes it haven't stop blinking, so I rebooted the router, and I flashed again openwrt whiterussian.
Tested on WRT54GL1.1
B.R.
Eddi