Accessing the Sun PROM on OpenBSD

After installing OpenBSD on my Sun Blade 100, the "stop-a" BREAK sequence no longer provided access to the PROM (which I expected to happen). While running OpenBSD, however, I found that it is impossible to access the PROM (key-words: while running...you can still access it before the OS loads).

problem:
How to access the Sun PROM when an OS other than Solaris is installed? When I shut down, I can see the PROM command line, but it doesn't accept input?

solution:
Once the OS starts to load, you will be unable to access the PROM like you normally can when running Solaris. You must reboot the system and send a BREAK sequence before the OS starts to load (on a Sun keyboard, this is done via the "stop-a" sequence). You will then have access to the PROM command line.

To make it easier, you could simply set the PROM variable auto-boot? to false so that whenever your system starts up, the OS will not automatically boot and you will be given a PROM command line.
To do this, use eeprom (or openprom if eeprom is not available) and do the following: 

   # eeprom auto-boot?=false
If your shell is trying to interpret the '?', just escape it: 
   # eeprom auto-boot\?=false