More detailed
Throttle
1. Cut the original throttle connection cable and left about 30cm/inch tail for it.
2. Open the throttle base and slowly & careful pull those thin cables (1.) out from cable cover. Be very careful and do not cause a stress to the thin cables solder joints.
3. Tape together those 15+1 thin cables. You could also use some flexible tube.
4. Cut off the connection cable remain and just leave the cable bend-protector (2.) on its place.
5. Pull the thin USB cable through the cable bend-protector and leave inside of the base 30cm/12inch tail to have enough slack for the later use.
6. Remove the vacuum-cup holder covers (3-4.) and pull the USB and thin cables through.
7. Nice clean and flat area (5.) for the additional pots and buttons to place. Another option is to do a complete separate switch/pot panel, which you can place anywhere you like. Fake MFD anyone?
Original picture is from
http://saitek.ru/other/x45inside/Additional base
8. The thin cables (6.) from the throttle soldered to the original cleaned 15pin D-connector (7.).
9. The USB cable (8.) from the throttle soldered to the PCB cables (9.)
10. The un-used stick button cables (10.) packed to avoid short circuits.
Un-used stick handle PCB’s and switches.