Ok today Elandrion taught me how to host with my airport.
Worked perfectly on the very first try!
I'll give the instructions for OS9, since that's what you should be playing rogue spear in, but I'm sure it's similar if not the same for OSX.
Ok here's what you do.
1) Make sure you update your airport software (I have version 2.02)
2) Open your TCP/IP in the control panels.
3) Write down the IP Address (10.0.x.x)
4) Open your Airport Admin Utility, which can be found here:
Macintosh HD -> Applications (Mac OS 9) -> Apple Extras -> Airport -> Airport Admin Utility.
5) Highlite your base station, and click "Configure."
6) Now click on the tab that says "Network"
7) Click "Port Mapping..."
Press "Add," and in Public Port, enter 2346
In Private IP Address, type in the IP you wrote down in step #3.
In Private Port, enter 2346
9) Repeat step 8 exactly, but replace "2346" with "2347"
10) Repeat step 8 exactly, but replace "2346" with "2348"
11) Shut the Airport Admin Utility, and save the changes you made.
12) Open Airport, and press "Turn Airport Off," wait about a minute, then press "Turn Airport On"
You are now ready to host Rogue Spear!
Once again, many thanks to *DAMN Elandrion, he was a great help. Maybe an admin could make this a sticky thread for anyone who wants to be able to host with airport.
--Snipie.