I have had the oven completely removed (which only took 5 min) to reinforce the cabinets so that it is more securely mounted. It certainly isn't mounted in there with much. I haven't seen up close how the microwave is mounted, but assuming the outer cabinetry is there (what you see when everything is installed), I would think you could easily retrofit the supports you need to install an oven with some hand tools. Some hand cut 1x2 or 2x2 lumber is what you'd need, as well as some glue, screws, and clamps.
You can see what I did here, at post #18:
http://www.trailmanorowners.com/foru...ad.php?t=10246
As you can see, it doesn't take much to mount the oven. That was 3.5 years ago, and I haven't had to do anything to the installation since that time.
Also, that thread is a reminder to everyone with factory-installed ovens to check all corners of the range to be certain the propane line is not rubbing up against it.
Dave