We have a WinPe boot key that we use for a variety of things. One of the options is to launch the V5 EETECH. I want to add another option to run recover for V6.1.3 clients. Would it be possible to add a single .exe that would be launched from a Winpe command prompt without having to add dozens of registry entries, and trying to load drivers which will likely not work? If not why ?
No it's not possible, because you need drivers to intercept the disk traffic and decrypt/encrypt it.
You also can't mix EETech and Wintech on the same CD, because the drivers are different.
Not in windows - you can't dynamically load a filter driver - it has to be hooked in as the OS builds out the driver stack.
And, WinTech is incompatible with the v6 drivers - you need to stick to one version or the other, you can't mix them up.