Frank,
It's not that hard. You must first determine which controller you will use, then learn how to program the knobs or buttons or wheels or sliders to call up sounds on the MJ.
I have an Edirol PCR 80
www.sonicstate.com/articles/article.cfm?id=69 It works great on channel 1. You can use a volume pedal and a sustain pedal. You split the Midjay where you want, and the style starts when you hit a key in the lefthand area (when you have it set to auto start).
You can do fills, intros, endings, variations, etc from the Midjay buttons, or you can use a Ketron footswitch to do some or all of them. I use a combination of both.
You can set up and save your assignments on the Edirol. You will need to read the manual carefully, but it is a pretty good manual, if you decide to use this particular controller.
You can call up any sound from the 64 preset sounds without a lot of trouble. You can also set the Edirol to make Bank changes and call up the sounds that are not in the presets. I haven't done that. Rather, I have edited the presets to include the sounds I use.
Placement of the Midjay in relation to the controller is critical. You must put it as close as possible so that you can easily press the buttons with your preferred hand.
I use an old two-tiered Ultimate Support a-frame because it is almost infinitely adjustable, and light-wight to boot.
In my opinion the key to using the MJ as an arranger is to set up as many registrations as possible. Every time I do a new song, I save the setup to registration. You quickly name them, then later edit the names on your PC via USB.
If you save a style and lyrics with the same name in the same folder, the lyrics are automatically pulled up with the style.
I prefer to put all the lyrics in the WAV folder, then if I want them to open I save the song as a registration. Either way works.
You will find that the overall E.Q. and the mic E.Q. is VERY sensitive. A change of one number does a lot. You won't need to e.q. much.
On the other hand the DSP (reverb and echo) seem to have a broader range of adjustment.
These are just thoughts that come to mind about things that gave me a little trouble as I set mine up.
If you have any specific questions as you get into it, I'll be happy to try and help.
DonM