When at all possible, you should use a binary image generated by Dynamic C for programming new core modules. You can compile to a file from your original source code using Dynamic C.
If you absolutely need to copy the compiled program from existing hardware, you'll need to use Dynamic C to compile a program to RAM that you can use to read firmware from flash.
The RCM4000 has an Ethernet interface, so you could use this sample (https://github.com/digidotcom/DCRabbit_10/blob/master/Samples/tcpip/http/download_flash.c) to download a copy of the entire boot flash.
You would still need to extract the firmware image from the downloaded "boot.bin". You can use Samples/RemoteProgramUpdate/firmware_report.c to find out how big the firmware image is, and then truncate boot.bin to that size for a binary you should be able to install with the Rabbit Field Utility (RFU).