The link you provided is for REG command not REGEDIT

y>reg export HKLM  cmd.reg
Operation completed succesfully.

lt@MC-TAVIANI:y>perl -e "system qq(reg export HKLM perl.reg)"
Operation completed succesfully.

y>dir *.reg

 Directory y:\

06/03/2015  08:54       191.906.582 cmd.reg
06/03/2015  08:54       191.906.582 perl.reg
[download]

Anyway you can simply do something to dump all root keys:

my @rootk = qw(HKLM HKCU HKU HKCR);
foreach my $root ( @rootk ) {
        my $ile = $root.'.reg';
        system qq(reg export $root $file);
}
[download]

That said untill now there is nothing about Perl in this thread.. So if we want something perlish as solution you can try Win32::TieRegistry: is stable, updated, and i use it since 10+ years to remotely create ODBC on winz systems. Looping all the keys with Win32::TieRegistry (or the name is Win32::TyeRegistry ? ;=) ) and write a Config::INI file, double quoting all strings, seems a feasible way

HtH
L*