Just ask the owner.
Whoever writes the source determines what commands they want to exist and who gets access to them. If you know what source he based the server on then you could just download that source and see what commands it has for pm's but he could have just as easily re-written the commands or added his own.
There's no single 5530 source, there's no 'standard' list of commands.
As such... #closed, talk to the owner of your server.