A vendor just sent me this script to decode their vendor message table. It's not just a simple lookup, but a concatenation with several events. I see guides on Python. Is that the only supported language for custom commands? Should I just use Python to wrap this? Any guides on this?
IMHO, this is a simple enough script, I would go ahead and port it to python as a scripted/external lookup. It is well worth the exercise and once you have done it once, you can add that to your Splunk toolbox.