Its been a while and I only set it up on an SL-1 but you define analogue extns as MOH sources 1,2,3 etc and then punch down your cd player or feed. The MOH feed that the person on hold hears is defined in the class of service of the extn or the acd queue.
You will got a more detailed answer in the meridian forum.
When I was born I was so suprised I didn't talk for 18 months