You don't actually have to use characters that won't appear in the string... and I guess thats not even possible, since text messages from other chatters are not calculable. (I suppose those messages are individually editable? :P) But if you escape that escaping-character, too, there won't be any problems...
Code:
var %encode = $replacex($1-,&,&1,$chr(3),&2,$chr(15),&3)
var %decode = $replacex($1-,&3,$chr(15),&2,$chr(3),&1,&)
