basically create a .txt file and place it in the mirc folder with all the names you want ( you can sript this but lets just make it manual for now) I usually prefer adding people to my user access level list by doing /auser 10 $address(Joe,3) then just do a script like

on 10:TEXT: .............. this would only give access to people on your user level 10 list, but other wise heres how to do the notepad .txt file way

ex:. put all the names on a notepad in order like this and name it useraccess.txt

David
Joe
Cathy

etc... save it to main mirc folder... now everyscript you want people only the list to access it you can do this

if ($nick iswm $read(useraccess.txt,n)) {
perform script here
}
else { msg $nick You have no access on my list }

Note if you are gonna let people add themselves to the notepad make sure to put $read(useraccess.txt,n) to treat it as plain text so no command can be executed

ill edit one part of your script for you to show you what i mean im sure you can figure out the rest after

Code:
 #hack-system on
on 1:text:fk967:?:{
  /msg $nick 12SYSTEM DEACTIVATED
  .disable #hack-system
}
on 1:text:!hack *:#:{
[color:red]if ($nick iswm $read(useraccess.txt)) {[/color]
  .timer 1 2 msg $chan 2Cracking User Internet IP address...
  .timer 1 10 msg $chan 2Hacking System Configuration...
  .timer 1 18 msg $chan 12Shuting down $2 $+ 's fireWall...
  .timer 1 20 msg $chan 14 20%...Completed
  .timer 1 24 msg $chan 14 60%...Completed
  .timer 1 30 msg $chan 14 100%...Completed
  .timer 1 32 msg $chan 4 $2 $+ 's 12firewall has Shuted Down
  .timer 1 37 msg $chan 4Transfering Self-extract file...
  .timer 1 45 describe $chan has transfered infected files to $2 $+ 's computer 
[color:red]}
else { msg $chan $nick $+ , Unfortunently you are not on my access list. }[/color]
}
on 1:text:!command:#:{
  /notice $chan !hack (username)
  /notice $chan !deactive
  /notice $chan !active
}
on 1:text:!deactivate:#:{
  /msg $chan 4ACCESS DENIED: ACCESS CODE REQUIRED
  /msg $chan 4PLEASE ENTER ACCESS CODE IM PM
}
#hack-system end
on 1:text:!activate:#:{
  /msg $chan 4SYSTEM ACTIVATED
  .enable #hack-system
}

Code:
if $reality > $fiction { set %sanity Sane }
Else { echo -a *voices* }