From direct experience, unless you have the source code (the flash access/security bytes in particular), you will Never get to the runtime code to upload & copy it.
In the fall of '10, I had a task to do the same. I thought the 711 series was early (primitive) enough to not have effective security, and spent a solid week finding otherwise. I had to disapoint the customer, but they appreciated the candor.
I use 908 & 9S08 series chips and Know that Nobody is getting My IP anytime in this century.
The most practical approach is to rewrite the project from scratch. BTDT X n, but good luck anyway... <<<)))
P.S. depending on the exact part number, they may be simply unobtainable.