Maybe not the best way:

c:\@Work\Perl>perl -wMstrict -le
"print join '', map sprintf('%03o', $_), unpack 'C*', qq{\r\n};
"
015012
[download]

See sprintf for  'o' template | format specifier.

Update: Or maybe:

c:\@Work\Perl>perl -wMstrict -le
"my $x = qq{\r\n};
 $x =~ s{(.)}{ sprintf '%03o', ord $1; }xmsge;
 print qq{'$x'};
"
'015012'
[download]