Well, my iTunes project is hung up. There are any number of remote-control applications for iTunes. I have downloaded several. iTRC seems to be the most mature.
All the Mac OS apps rely on activating Apple Remote Events on the host machine, and there my troubles start. Remote Events use a creaky old protocol, ‘eppc:’ which no longer operates properly and in particular has difficulty passing user IDs and passwords.
So, the long story short is that while the desired functionality is supported and documented within all-Apple products, it’s currently fuct. I will spend a bit more time on it tomorrow but it looks to me as though my desire is unlikely to be fulfilled in the manner I had been visualizing.