I don't use a C4, but I do use an MCU & XT. This may or may not work, I've never tried to change the number of EQ bands available BUT if it is possible it will almost certainly be done by editing the ini file.
Again I have no idea whether there is a separate one for the C4, it uses the MCU file, or use an ini file at all but they are easy to edit. There is an explanation of how to change various settings, defaults, rotary assigns, etc in the header file (which you can edit in a text editor such as Notepad).
I've certainly managed to add the Sonitus compressor to the MCU dynamic button by editing this file and it may well be possible to open up the other two EQ bands to it as well. I'd suggest working on a copy of the file and renaming the original, then if you screw it up you can delete the 'new' and go back to the old.
See
THIS POST for how I added the compressor which will give you an idea on what to change for the EQ.
Of course if there is no ini file for the C4, doesn't use the MCU one, or just doesn't work then my apologies for getting your hopes up.
