Is there any reason it has to be a regexp? Not that it isn't an interesting regexp problem, but Text::CSV_XS with 'sep_char' set to ':' should solve your problem - as well as several of your other delimited-text processing problems. Something like this (from `perldoc Text::CSV_XS`):

$csv = Text::CSV_XS->new({
   'quote_char' => '"',
   'escape_char' => '"',
   'sep_char' => ':',
   'binary' => 0
});

It's quite flexible...

-beernuts