alias a3 {
/set %colour3 [ $1 ]
//echo %colour3 "Message"1 colour has been set.
}
You do not need / in a script, mirc does it automatically for you. & try this next time.
alias a3 set %colour3 [ $1 ] | echo -a %colour3 "Message" Colour has been set.
Not saying 1 liners are better, just saying for a code this short might as well.