I guess it all depends on the actual method your DR company uses with their version of Ghost.
Basically, once you have booted to WinPE and made a network connection to the Ghost server, instead of running Ghost32.exe with a bunch of command line parameters, you just call the appropriate version of Imagex with the necessary command line options. However, it is worth mentioning that unlike Ghost, imagex does not automagically use existing partitions, so it is worth starting with a clean drive by scripting some partition clear and create operations using the DISKPART utility in WinPE.
The WIM does not necessarily "build" the image as it deploys, as I have created builds on XP which were then sysprepped, and compressed into a WIM file. The Wim files were deployed and the machine would then complete the build by running a scripted mini setup.
Bear in mind also that if you create an image of a non-sysprepped Windows 7 build and deploy it to a different machine, even if an identical model, Windows 7 will detect this and will need to be re-activated. That should be no problem if you use a KMS server but it is something else to think about. Running sysprep also strips out any activation so you would again need to have a KMS server or a volume MAK key in your build. Apologies if I am covering old ground but there's no indication of your design decisions in the earlier postings.