There should be an option to control the bandwidth of the dcc send.

e.g: if i leave my mirc connected and dont want it to 'eat' all of my BW...i can set it to send at 10k/s, even if my line can do more.

thanks!

You can already do that. Hit Alt+O to open mIRC Options, go to DCC > Fserve. Change the "Total Max. Cps" number to anything you want (cps = bytes/sec, so if you want 10 k/s, enter 10240). Then start all your sends with
/dcc send -l nickname filename
instead of
/dcc send nickname filename
Even though the setting is in fileserver options, it applies to normal dcc sends too.

In case you were meaning on recieving files also...
There are some 3rd party apps out there that limit/control the bandwidth to programs, sorry i cant actually remeber there names but a google search should find something. I tested one out once and it worked fine, I could set the inbound and outbound bandwidth, and mirc just sat right around that point.

netlimiter is nice for that

lol I think thats the one i tried just couldnt remember the name.