I am not sure about the Linksys router range, but I know on many models of that quality, it allows port forwarding on a slightly betwer details than some.
My router gives me the option to forward up to 10 single ports, and a DMZ (all other ports to one IP). This is isn't the best of configuration, but it is suiting me for now.
Other routers are the same, but allow port ranges, rather than just single port numbers to be forwarded.
A single range of 10 ports, will allow up to 10 concurrent DCC connections (chat, sends, voice, video) at one time. EG, forward ports 15000 to 15009 to your machine. Setup mirc to only use this range for DCC requests (see DCC options).
This may possibly work, however, it may not.
As posted earlier in the thread, not all routers operate correctly, and will drop packets (not allways your won router, it may be the ISP's).
EG, 2 machine on my network 192.168.1.2 and 192.168.1.33.
My public IP is 212.159.100.245 and all ports are forwarded to the 192.168.1.2 machine.
When I want to browse the intranet server on my network, I use my dynamic DNS hostname (coz I can't remember my IP by hart yet).
This works fine while on the internet. However, when on 192.168.1.33, any request for the IP 212.159.100.245 is dropped by eithe rmy own, or my ISP's router.
If it's my own router, then there is nothing I can do, toher than urchase a better router. If it's my ISP's, then it could, but wont be fixed.
It is designed to prevent routing loops. Allthough TTL data will normaly prevent it, it quciker to drop a packet, that was never designed to travel that line in the first place.