heres my understanding:
you have a machine from japan which outputs a monochrome (chroma) video signal through one wire. you were using it with a commodore monitor before, but now you cant and you want to use it with your tv instead. when you plug it into the yellow connector on your tv you get a rolling or flickering picture.
now, from this i can almost definately say youre in a PAL country (what country do you live in?).
the problem is that japanese video works at 60Hz, and european types work at 50Hz
the commodore monitor has a V-hold knob, which adjusts the Hz value the monitor is looking for, so you can use a chroma signal from any device no matter where it's from.
if your tv has a v-hold adjustment then you can use that to fix the problem. otherwise you can check the tv menu to see if theres an option (look for "colour system" or something like that) to change the tv to ntsc. it might be that your tv does support international formats, but because youre using a monochrome signal it's getting confused.
if your tv has neither of these, im afraid the device will not work on your tv. you'll have to look for a tv which it will work on, most sony trinitron's should work.. but the only way to tell for sure is to try it. (or if youre buying a new tv, ask the salesperson if it supports 60Hz video or ntsc video)
the other possibility is that the divice itself could be modified to output 50Hz, but we wont know unless you tell us the model numbers etc, and if its as unusual a device as you say, it's possible nobody will know anway.
in the end it might be cheapest to just buy another commodore monitor.
i hope i've helped.