Is there a way to replace the envelope template used in the Tools =
Envelopes and Labels command?

I like being able to select an address in the letter and having it
automatically entered into the Delivery address portion of the dialog box of
Tools = Envelopes and Labels. I also like having the option of turning on
and off barcodes when needed. But I have some graphics I'd like to print as
part of the return address. Messing around with bookmarks and the {BARCODE}
field is a bit of a chore. Any ideas or hints would be appreciated.