If you're trying to install the CRC front end to the car that has the Corally front end on it then it's pretty simple.
Remove the two screws on the bottom that hold the central front suspension brace on and the whole front suspension should come off in one go.
There are 4 larger holes in the front of the chassis of the SP12X designed for the AE/CRC front suspension. Use the 4 screws that came with the CRC kit (pre tap the lower arms with the metal screw) to screw it on.
Alternatively you can just look at the other SP12X I sold you as it already has the CRC front end on it.