I assume posting code would violate some sort of copyright, but I have modified MCLOADER to do all sorts of different things.

If you are brave, you can dissassemble the .HEX file and look for where it sets up the USART Change those (probably two) 'movlw' lines and re-assemble.

Open MPLAB, import the .HEX file and choose VIEW MEMORY. Although there is probably an easier way, I set up a "send print to file" printer and chose <CTRL><P> to save the dissasembly as txt.

Use a DIFF program (I use ARAXIS) to compare the 20MHz and the 4MHz bootloaders. The rest is easy.