The visible light camera assembly (sheet metal cage) looks very similar to what I found in my Sony EVI-D80 PTZ camera. Maybe MIC used Sony OEM module. It is a nice camera and the video is even digitized to add OSD but then it is converted to crappy S-Video for the output :(. Reverse engineering is tricky as it is Sony thus full of custom Sony parts. I would rather replace the sensor with something fully digital and add something like CY7C68013A for the USB interface + interfacing to some small MCU to control all the motors, but looming the non-original cabling through the PTZ mechanics might be tricky.
Also, if I'm not mistaken, it looks like the motors in your cameras are made by Maxon. Every time I see Maxon or Port/Escap motors somewhere it is somehow an indicator of a quality product :)
Some even have an extra device mounted on top (not sure what it is, maybe an SWIR or MWIR camera, or other exotic wavelength camera of some kind).
(http://www.distek.ro/client/images/1328039954+Flir-HRC-Border-Security-Surveilance-Infrared-Thermal-Camera.jpg.original.jpg)
Flir-HRC-Border-Security-Surveilance-Infrared-Thermal-Camera.jpg