You could try creating a BOOT.CCC file which contains the "SM" command.
Topic?> INFONBOOT
INFONBOOT>
-- XXDP V2 CAN BOOT TWO MONITORS (XXDPSM OR XXDPXM). THE "SM" OR SMALL
MONITOR IS FOR SYSTEMS THAT ARE 28K OR SMALLER IN SIZE, THE "XM" OR
EXTENDED MONITOR IS FOR SYSTEMS LARGER THAN 28K. THE "SM" MONITOR
WORKS LIKE THE MONITOR OF XXDP+ V1 AND WILL RUN ALL PROGRAMS WRITTEN
FOR V1. THE "XM" MONITOR OFFERS THE NEW FEATURES ADVERTISED IN XXDP V2.
BY DEFAULT YOU WILL BOOT UP THE "XM" MONITOR PROVIDED THE SYSTEM HAS
ENOUGH MEMORY AND MEMORY MANAGEMENT CAPABILITY.
START-UP FILE BOOT.CCC
-----------------------
AT BOOT TIME, A START-UP FILE BOOT.CCC WILL BE EXECUTED AS A CHAIN FILE.
IF THIS FILE DOES NOT EXIST, THERE WILL BE NO WARNING MESSAGE, BOOT WILL
CONTINUE AND BY DEFAULT THE "XM" MONITOR WILL BE BOOTED UP. IF THE FILE
EXISTS, IT MUST CONTAIN ONE OF THE TWO COMMANDS LISTED BELOW. ONLY ONE
OF THE TWO COMMANDS MAY BE USED AT A TIME AND IT SHOULD BE ON THE FIRST
LINE OF THE FILE WITH NO LEADING SPACES. IF THE FILE DOES NOT CONTAIN ONE
OF THE TWO COMMANDS IT WILL BOOT UP THE "XM" MONITOR. NOTE, IF THE SYSTEM
DOES NOT HAVE MORE THAN 28K WORTH OF MEMORY OR MEMORY MANAGEMENT CAPABILITY
THE "SM" MONITOR WILL BE BOOTED UP.
SM - BOOTS THE "SM" MONITOR.
QUIET - BOOTS "XM" MONITOR IN UFD MODE. (SYSTEM.CCC MUST EXIST)