Shooting with an overlayed guide/reference image?

[dreamrthts]

Hi there. I've done several google searches to absolutely no avail on this topic. I'm looking for a way to accomplish something akin to (in my imagination) inputing an image into the camera to act as the digital grid display would, as a transparent overlay to what I'm seeing through the viewfinder. I could then position myself/camera and the item to align perfectly with a reference image I want to match as closely as possible. In-camera software? Hardware? Other??

I've read about the in-camera dual exposure features, but what I need to do would be more like being able to see one exposure WHILE framing the next shot over it (as opposed to combining the two after both have been shot).

Suggestions welcome!

[dreamrthts]

Thanks Waddizzle. Agreed, that would be the ideal! Unfortunately the challenge here was to match up some shots for which tripod/setup details are not available (were never documented).

Even moving forward for new pairs, documenting the initial setup won't help all that much. Due to the fact that thes are vehicle repair shots, the car, even if it's parked and never moved, shifts slightly as its weight shifts, workers are in and out of it, etc. I could do a time lapse, but it's just a before/after series of images focused on various components (inside and out) that's really needed, not to mention the camera/tripod must be removed during the work so as not to impeed. 

I don't expect to get PERFECTLY aligned images, but at least saving my self hours of Photoshop alignment and distortion with the in-camera ghost image solution will be welcome! Can't wait to try it.