Yes. The slashes are just a technicality for preg_match(), so that you can specify modifiers along with the pattern (like "i" for a case-insensitive match). Having the user add that to every regex would be both tedious and error-prone, so the plugin already does it for you. All you need to do is enter the regular expressions by themselves (one per line).
The only downside is that it makes all matches case-insensitive, so you can't distinguish capitalized from non-capitalized localparts. However, I thought that was an acceptable tradeoff.
It would've been more consistent for PHP to make the function preg_match() accept modifiers as flags like PREG_UNMATCHED_AS_NULL, so that you wouldn't need to add the slashes around each expression, but alas that's not how PHP works.