OK, then the only way there should be a problem with this is if mIRC or the IRCd is preventing all 10 from being set at once
Code:
 alias ban.all {
.mode $1 +bbbbbbbbbb $2 1 $2 2 $2 3 $2 4 $2 5 $2 6 $2 7 $2 8 $2 9 $2 10
}

Usage /ban.all <channel> <nick>

Note: There is no error checking in this.