You could have the 3 keyboard rows in separate strings, then use $mid, $pos and other related identifiers.
In order to implement the wrapping effect you could either check for boundaries (if <letter position> == 1 then wrap) or use the mod operator % with $calc, eg $calc(10 % 3).
You may also need the isletter /if operator.
You'll need to look all these up in the help file. Start by typing /help text and number identifiers. Happy scripting!
