A HUGE THANKS to Jerry, Simon and John for their responses...and unfortunately, it seems NOT doable ......
....and it would be wonderful if anyone CAN make this work on the FR1X and let me know : )
well lets give this analog method a shot Joe..
first off, you have this desire/need/idea of switching keys on the fly which
means you have the DESIRE to accomplish this somehow, and so you are motivated
perhaps in a different way than in the past
so
pick one of the songs you think this jump would be valuable and fun to do
when you play it
now focus on the PHYSICAL PATTERN of your Bass throughout the entire song..
repeat and keep the focus on your physical left hand finger motions..
now play the song ONLY on the left side.. repeat.. repeat..
now just move your hand up to a different starting note and
REPEAT THE PATTERN
if that worked and you think you are hitting everything correctly on the Bass,
then just close your eyes and try playing the Melody along with it
hey, it's worth a shot !
good luck
natural transposition is admittedly easy for some of us, and seemingly impossible for others,
that's just the way it is..
but it does not necessarily have to be a life long condition