It should be fairly transparent to you except when you make your socket connection. Check out this usenix article. The article concerns network connections with perl4 which is pretty old but then again so is X.25. Basically wherever you use AF_INET and PF_INET in your code, you would need to change to AF_X25 and PF_X25. I'm sure other caveats apply.

As for info on X.25, just google.

-derby