use Parse::RecDescent;

my @lines = << 'EOINST';
// COMMAND ARG1-VALUE,ARG2-VALUE, +
   ARG3-VALUE,ARG4-VALUE, +
   EVEN-MORE-ARGS
// ANOTHERCOMMAND
* and a comment
* or two
EOINST

my $parse = Parse::RecDescent->new(join '', <DATA>) or die "Bad Grammar!";

use Data::Dumper 'Dumper';
print Dumper [
$parse->Instructions("@lines") or die "NOT parsable!!\n"
];

__DATA__

Instructions: command(s)

command: multiline_command
       | singleline_command
       | comment

singleline_command: 
	'//'  /.*/
		{ {command => $item[-1]} }

multiline_command:  
	'//' /(.*?[+][ \t]*\n)+.*/
		{ $item[-1] =~ s/[+][ \t]*\n//g; {command => $item[-1]} }

comment:
	'*'  /.*/
		{ {comment => $item[-1]} }