UPDATE (Nov 02, 2013) - mIRC SUPPORTS THIS. Leaving this here for the archive, though. Enjoy!

The basic function of this snippet is that it can be used to perform MULTIPLE commands at once.

Usage: /mcom /Command1 | /Command2 | /etc...

Each command that you wish to execute is merely seperated by a |. This new command can be used within scripts that you are writing or it can be used at the command line in mIRC.

alias mcom {

; This var command is setting two variables:
; %s - This is set to the entire line of commands.
; %i - This is set to how many different commands
; have been set between the | characters.

var %s = $1-, %i = $gettok(%s,0,124)

; This while intitializes a loop. While the
; variable %i (which was, if you remember, 
; set to the total amount of commands) is 
; a value greater than 0.

while (%i) {

; The next section sets a 0 millisecond delay 
; between each command. The reason for this 
; is that mIRC does not having multiple 
; commands sent at once. We set the timer 
; name to $ctime + %i; this ensures that the 
; timer name was never used before (almost 
; certainly). After we set all of that and the 
; 1 0 values (saying we want it to only happen 
; 1 time with an interval delay of 0ms), we see 
; that the timer executes a command extracted 
; from the %s variable using %i)

.timerMcom $+ $ctime $+ %i -m 1 0 $gettok(%s,%i,124)

; We decrease the value of %i by 1 everytime 
; so we ensure that the loop will eventually stop 
; when it has reached the end of the amount of 
; commands in the request.

dec %i

}