NetGear RT314

I just installed a netgear RT314 router. I would like to know if I can keep a port open on all my network rather than by IP address. For example I want to keep ports open on many systems to run MIRC but from what I see I have to do this by IP address which would use up the 12 menu settings I have.

Also , how would I set up a DMZ for a more than one system. I would appreciate detailed answers or if you dont know, ddirect me to a good site that can help ( I have not found good information on netgears site) For some one who can give me a detailed correct answer, I will up the points!!!!!

Thanks