Here is a patch that will allow you to move the MOUSE port to some
IRQ other than 3/4, and have it work on ISA machines with
Serial mouse..

----- Cut Here -----
FILE C:\MYMOUSE.SYS
VER 1813   891E890181E3000FFEC7
CHA 1813   891E890181E3000FB7xx
;                            __ change this to IRQ number required
;
;  This patch changes the IRQ for a serial mouse
;
;  The standard calculation is as follows
;
;  Port addresses = 03F8, 02F8, 3220, etc...
;
;  use .x.. nibble of port address +1 as IRQ number
;
;  the code above is
;
;
;  Mov BX,port_address
;  AND BX,0h0F00
;  INC BH               < we are replacing this instruction with
;                         MOV BH,xx to force a SPECIFIC IRQ number
;                         For example below to IRQ 5
;
;
;  CHA 1813   891E890181E3000FB705
;
;
;  Note: this does NOT change the PORT ADDRESS, so these are expected
;        at their STANDARD location....(whatever bios say at 40:0)
;
;  To apply this patch, copy \OS2\MOUSE.SYS to \MYMOUSE.SYS (or whatever)
;  edit the FILE name above to point to MYMOUSE.SYS (if different)
;
;  from an OS/2 command prompt type PATCH MOUSE.PAT /A
;
;  Edit config.sys, change the DEVICE=\OS2\MOUSE.SYS SERIAL=1
;                           to DEVICE=\OS2\MYMOUSE.SYS SERIAL=1
;
;  REBOOT