Sonic XPRS 2 and Netmeeting

I need to open my firewall to be able to run netmeeting 3.01. I have a Sonic XPRS2 firewall orunning NAT. I want wan users to be able to come in from the internet to a local machine on my LAN that is hosting a netmeeting call to share an application. Can anyone tell me what I need to do in my firewall to open it to netmeeting. i have been to Microsoft and found that netmeeting article that pertains to firewall but that fix does not appear to be enough. Be specific. Thanks in advance