Maybe you could put a couple of small scripts at the root of your art dir which launches each of your preferred viewers. They should probably only contain the one line which RUNs (or WBRuns, if you prefer) the viewer with its full path, similar to TribbleSmasher's suggestion. Then give them each an icon set to start from Shell.
Not sure which OS version we're dealing with, but I think something like that would work at least back to 2.1 or thereabout.
Best regards,
Niels
