I have ported the Motorola assembler and monitor. The manual is in the files, it is the software from the 

Motorola MC68000 Educational Computer Board (MEX68KECB). There is a site with more info here: http://www.easy68k.com/paulrsm/mecb/mecb.htm

It is the most capable monitor available for the 68k. It offers an in line assembler, trace and breakpoint routines. I have tested them and they are now all working on the Merlin. Here's a quick demo showing the assembler and a trap function.