You could use a Mapped Instrument object in the environment, which really isn't complicated at all, but it could be a pain in the posterior getting the names in there - I can't see a way of pasting in an entire set of names, which would be pretty handy.
There's a section of the manual that deals with that, which is worth a read (and, in my case, probably a second one while I take it in).
You can usually use a patch editor-librarian program like Sound Diver or MidiQuest to copy and paste the patch names (one bank at a time) into the patch name list of a multi-intsrument object in the environment.
That's what I do. Works like a charm.
"My first copy of Logic came on Floppy disks"
And you will need to setup bank change commands for your particular instrument, if it does in fact have several banks of internal patches. Logic comes with a selection of bank change commands, one of them will almost always work.
My first copy of Logic came on floppies, two of them I think and was MIDI only, moved up to Logic_Audio at version 3.0 I think.