I would think shortening them would be difficult, depending on how much travel they need, you may be able to order some that could be adapted, that would be closer to the right length. Try surplus center, thats where I got my cables for my tcase shifters.
After looking at it again, I will possibly be able to just use rod, it is almost a straight shot from where the shifter will mount back to the shift mechanism on the transmission.
Also appears that the shift pattern will still be correct afterall.