I used this .bin file here: http://downloads.nas-central.org/Users/timtimred/lsppchg/
so I can vouch for that one (at least it booted with the network cable unplugged - then it went crazy with DHCP requests when I plugged it back in but that was the OS, uboot had already done its job). The file there is for an HG. If you don't have an HG, use the one here instead: http://downloads.nas-central.org/Users/timtimred/lsppchd/
For the one I used I get:
$ head -c 52 u-boot-lsppchg-1.2.0-r2.bin
'VU-Boot 1.2.0 (Apr 10 2007 - 19:13:32) LinkStatio$
The problem with trying to build your own currently is that the git repository referenced in the instructions is gone, you have to get the uboot source from somewhere else as someone mentioned in another thread.
Interesting, when I do a head -c on the u-boot-hg.flash.bin file I currently have, I get:
'VU-Boot 1.2.0-g6af43833-dirty (Aug 16 2007 - 10:43:13)
So does that mean that your 1.2 is different than my 1.2?