I am trying to get the Microsoft mouse to appear during the system 
   boot. I added the line...

	   device 	mms0	at isa? port "IO_MMS1"	irq 12

   to  the kernel parm file...

The `mms' driver is for Microsoft InPort mice (and compatibles).
These usually aren't configurable to IRQ 12.  Does your mouse plug
into a special card, the serial port, or something that looks a lot
like the keyboard port?