Since *IMGCLG is a valid object type for a SAVOBJ command, could you not SAVOBJ the image catalog to a SAVF then FTP the save file over to the production machine?
The *IMGCLG can be copied via perhaps SAVRST or SAVRSTOBJ. Or it can be saved into a savefile that can be FTPed (or other transfer methods) and restored. Or you can simply load the image catalog entries to the production system directly from where they are on the on the development system — all you should need to do is use a /QFileSvr.400 directory entry as the location. The images can also copied through /QFileSvr.400 and then loaded, but you might as well just do the loads.
What works best for me is to FTP the IFS directory location to the other machine
First in the IFS create a new directory under Root where you want the IFS images to be stored. This will match the IFS directory that you set up on the DEV machine.
The FTP steps are:
Enter ID and Password for that machine
NAMEFMT 1 (This sets FTP to use the IFS instead of the Library)
CD /V5R4UPG (Or what ever name you called the IFS diectory where the images are stored on the DEV machine)
LCD /V5R4UPG (again what ever name you called the IFS directory on the production machine)
BIN (to change to binary mode)
MPUT /V5R4UPG (This sends over the entire directory to the new IFS location)
Then once the IFS entries are on the new machine create the image catalog or just restore the savf of the *IMGCLG noted above.
The Image catalog is only a pointer to where the images are actually stored on the IFS.