/ban -k $hget(shitlist,$address($1,2)) $1 2
Now for an explanation:
/ban is the actual ban command
-k tells mIRC that there needs to be a kick as well
$hget(shitlist,$address($1,2)) looks up the address in the shitlist hash table and returns the data stored (in this case the channel)
$1 is the person's nick
2 is the address mask for the ban
