The pin diagram for FC-7 operation is available on the web (maybe even here if you do a search!). But it's going to depend on whether Ketron use the same polarity switches as Roland/Yamaha. Korg use opposite polarity.

You can get a decent break/fill by using a button for break, then hit a fill button on the '3' or '4' of the bar. Easy enough if you use foot switches and put the variation select (with auto fill on) next to the break.

One more tip... get a good case! No bags. Very few parts are still available for the BK9. Especially the slider board. Mess that up, it's going to be hard to replace. The individual sliders can still be found, but if you mess up the board they're soldered to (or any of the main boards go bad) you may find it hard to use.

Treat it with care, it's the last of its breed!