Make a 'Convert' formula into an 'Action'

I have a Convert function that puts the Track number in front of the title and prepends a 0 if the Track number has less than two digits:
$ifgreater($len(%track%),1,,0)%track%-%title%

How do I make that into an Action?

Just use the $num function instead.

$num(%track%,2) %title%

Will ensure that all names have a 2 digit track number and add the leading 0 as necessary.

To use this in an action, you can use Format Values, and the above line to format Title.

Perfect, thanks for the help!