Pushback Panel V2.0 Program
There is a program that was made for FS9 that did a great job of handling Pushback Operations with pre-recorded sound files. It also included angles of pushback (not just the 90 degree, but other smaller angles).
This program was freeware and was called Pushback Panel v2.0 for Microsoft Flight Simulator 2004. This panel is based on XML gauges by Rob Barendregt. It is intended for Pushback operations.
Goto this link for more information:
http://harrierpanels.avsim.ru/eng/pb.html#pb2
I do have the zip files for PB 2.0 and the zip file pb2os.zip (that is a patch) if you cannot locate them. The patch enables Pushback Panel v2.0 to use Wingfold command in FS2004 to toggle ON/OFF the Project Opensky Pushback truck ( PTS-1 ). The patch comes with a default bitmap (posky.bmp) of Project Opensky Boeing 767-300 V4 (Air Canada livery) that can be replaced with any other.
Finally, I know FS9 programs can be made to work in FSX, so this would be a good one to figure out. Also, FSUIPC would then be setup with your Overhead switch/button to trigger the wingfold command and thus trigger the pushback panel.
I've used this panel in FS9 and it worked fine, it just needs a way to be brought into FSX...