I don't have the answer.
I looked in my favorite download site,
Major Geeks and came up empty (not even close).
But, I really like the question - I do a lot of automating in MS Office and this is a good challenge.
All I can figure is to have two images (the background) and the foreground (or two layers of a single image). Then, all you have to do is figure out how to create an image with the text only then merge it with the background image.
I suspect you could write some sort of routine that could run in Photoshop (or even Paint Shop Pro) that would do this. I think one key is NOT preparing the images in bitmat form but the native format of either program where the text really is text (and is manipulatable as such) and not reduced to a bitmap yet. You can save the merged image as a bitmap.
Even if it doesn't work the way you hoped, keeping the text as a distinct layer in your template image should make the entire task take no more than 2 minutes to complete.
Another off-beat thing I thought of is to store the image in MS Word and create a text-field placed over the image. You can feed the parameters of the text-field to Word via VB simultaneous with opening Word. Take a screen shot, save as bitmat and you are all set. Easier said than done, tho.
If you do figure it out, pls reply with how you did it.
Again, not the answer you were looking for but my best shot.