Have a look at my solution to the problem I had with DUO controller (for Bresser EXOS2 or LXD75 mount).
I couldn't change the
firmware (because the processor was read-protected) so in order to accomodate the required 5x faster motor speed, I introduced the PLL clock multiplier chip: (
http://www.iceinspace.com.au/forum/s...ighlight=LXD75, post #11).
This clock multiplier can be controlled on the fly and has 2x output (as well as number of other rates)