I don't know but with my quick play with the FX and reading
This from the JJOS site that is what I had worked out so far.
It seems you can change it to Track mode from the Mixer screen though, rather than GPE, which is where I was looking before.
http://www7a.biglobe.ne.jp/~mpc1000/os2xl/mixer.htmI would guess that also changes it in the GPE screen as it would be a bit strange to be able to send a program and a track to the effect as that would effectively be trying to send it there twice...
As I said that was all I had managed to work out so far and was hoping for some further pointers. I know there's a lot more that can be done than I've got my head around so far!