Leonardo & Micro — Changing Timer Pin Mapping Registers: Help needed

Hi everyone,

Short version of a long story:
It's about a Arduino Micro (32u4) and I need to change the mapping of the timers to the board pins.
I have read lost of stuff on the internet but the learning curve is too steep!

Pin D11 can also be set to use timer 1 output (OC1C), but the Arduino library uses it for timer 0 (8-bit). To use it on timer 1, it must be done by setting the appropriate registers.
Pin D10 (PB6) also has a timer 4 output (OC4B), but the Arduino library uses it for timer 1 (16-bit). To use it on timer 4, it must with the registers.

That is exactly what I need.
Pin D11: OC0A => OC1C
Pin D10: OC1B => OC4B

Can somebody give me the code fragment that will accomplish this?

Is it advisable to change the Arduino pin mapping directly in the 'framework'?

Many thanks in advance!
Christophe