OBP UPGRADE ON SUN ULTRA 10

I have a Sun u10 that I have installed Solaris 10 on. Unfortunately,
after the successful installation, the system panics and reboots each
time it comes up. I have identified the problem as the system needing
to upgrade the OBP. The problem is that Sun no longer issues the
upgrade on cd anymore. The file is actually a special patch. What
makes it special is that it must be downloaded and located in the
root (/) directory....which is unavailable, as the system never
completely boots up. Does anyone know any solutions or work-arounds
for this problem? Thanks!