Since you are dealing with arbitrary Internet addresses, you either need to know someone's address and connect to that, or connect to some server that helps you find each other. Some options:
1) Before each session, go look up your IP and then tell your friends to plug that into the patch. (you could use some site like whatismyip.com like Scott suggested)
2) Get a static IP address or domain name, and hard code the Max patches to connect to that. I think you can have a domain tied to a dynamic IP - there are software tools for this but I don't know much about it.
3) Setup a server with a known address (static IP or domain name) and hard code your Max patches to connect to that in order to find each other. Now you are getting into developing custom client/server software. This is probably more trouble than it's worth, unless you have experience doing such things.
Regardless of your choice, you may find you have trouble connecting unless you poke some holes in your router's and computer's firewall settings.
If you have Jitter you can ask that website for the IP address from within Max. Here's an example. Please note my knowledge of [regexp] is pretty poor but this seems to work if you give it a few kicks first.
Quote: firstname.lastname@example.org wrote on Sun, 26 October 2008 14:28
> If you have Jitter you can ask that website for the IP address from within Max. Here's an example. Please note my knowledge of [regexp] is pretty poor but this seems to work if you give it a few kicks first.
I was getting a "PCRE error -10" printed to the max window the first time I tryed to send the text out of [jit.textfile] which could be avoided by opening it and closing it again every time new html source is [jit.uldl]-ed into it. The error code is less than enlightening but I did stumble across another example on the forum and the response seemed to be that perhaps some of the characters in the text are being misunderstood or are confusing the regex parser due to using different character encodings. I just wanted to mention that in case anyone could shed some light on the matter but it isn't particularly important.