windows image for drivers. Please help.

This is kind of a complicated situation i am in. Basically, im trying to take a hard drive that has windows 7 installed on it, and install a few basic drivers to it while its connected to another workstation in a external usb tray.

Lets call my workstation im on right now c: and the hard drive im trying to install drivers on g:

Now what i want to do, is mount a windows7 image FROM g: TO c:. once its mounted, using DISM, install the drivers to the image, then unmount the image FROM c: back to g: Still with me?

I can mount the image fine. I can install the driver fine using dism.

My question is exactly what .wim file am i supposed to be mounting from g:??? which .wim file do i need to mount and add drivers too. This has been pretty frustrating to say the least. Any help would be greatly greatly appreciated. Thanks.