Building on the submission by ikegami:

package Date::Manip;
use warnings;
use strict;
use Carp;
use Exporter;
#
  our @ISA;
  our @EXPORT;
  my $backend;
  if    ($] >= 5.010) { $backend = 'Date::Manip::Perl5010'; }
  elsif ($] >= 5.008) { $backend = 'Date::Manip::Perl5008'; }
  elsif ($] >= 5.006) { $backend = 'Date::Manip::Perl5006'; }
  else { croak("Perl $] isn't supported\n"); }
  my $backend_exp = $backend . "::EXPORT";
  eval "require  $backend; $backend->import(); return 1;" or croak "$@
+";
  { no strict qq{refs};
    @EXPORT = @{$backend_exp};
  }
  
  unshift (@ISA, $backend);
#

1;
[download]

We pick the correct version of the module to use. Then load the module file and import the symbols dynamically, with an eval. Then we setup the @EXPORT list so it is available when the ->import() subroutine runs as part of use, the symbols are imported into Main::.

Update and Postscript:

If the package statement in the per-version Date::Manip's are left as-is, the following code is preferred:

package Date::Manip;
use warnings;
use strict;
use Carp;
use Exporter;
#
  my $backend;
  if    ($] >= 5.010) { $backend = 'Date::Manip::Perl5010'; }
  elsif ($] >= 5.008) { $backend = 'Date::Manip::Perl5008'; }
  elsif ($] >= 5.006) { $backend = 'Date::Manip::Perl5006'; }
  else { croak("Perl $] isn't supported\n"); }
  eval "require  $backend; " or croak "$@";
#

1;
[download]

This should work well.

Good luck. -c