how to DCC chat with channel (not with nick)

Short answer: you can't. DCC means Direct Client-to-Client .. not Client-to-Multiple-Clients.

how to chat with channel
it are unaffected by server lag ( tool or soft for it )

The only way to chat in a channel is to enter it. There's no other way, conventionally speaking.

There is such a thing as "party-line" scripts; however, they are affected by lag, just like everything else on the Internet is.

Whats the point of having a channel if you're going to chat on DCC anyways.. >:d Seems kind of redundant to be on a DCC chatroom and a channel at the same time.

Well if the channel dosn't have +n(no external msgs) mode on then you could /msg #Channel from outside the channel

Even still, they mentioned having the complete channel in a dcc. What, so they can just sweed out the /msg #channel external messages? Still seems redunsdant, and more work than it's worth.

Yeah, guess you're right...