This modules has the same interface as the much faster 'Digest::MD5'. So
you can easily exchange them, e.g.

BEGIN {
eval {
require Digest::MD5;
import Digest::MD5 'md5_hex'
};
if ($@) { # ups, no Digest::MD5
require Digest::Perl::MD5;
import Digest::Perl::MD5 'md5_hex'
}
}

If the 'Digest::MD5' module is available it is used and if not you take
'Digest::Perl::MD5'.

You can also install the Perl part of Digest::MD5 together with
Digest::Perl::MD5 and use Digest::MD5 as normal, it falls back to
Digest::Perl::MD5 if it cannot load its object files.

For a detailed Documentation see the 'Digest::MD5' module.