Under the agent section Lexicon of the options in mirc. There is a kick arse list there.

I know this is a stretch but is it at all possible to do this with a dialog list function without using outside help from .dll's or anything? I'm thinking a possible whileloop and a whole lot of $chr(32)'s
Or you can create an alias such as
alias sp { return $replace(s s s s s s s s s s s s s s s s,s,$chr(160)) } $chr(160) being alternate to a valid working spacer then $chr(32) the s are being using to be replaced with 160 in the $replace function so with that kind of script you can put the syntax in your script
First text here $sp Second Text here and will create the Gap accordingly