What you can do for your programs is change the Shebang to point to #!.../home/localperl/bin/perl --

or  #!/usr/bin/env perl and adjust your $PATH to include ~/localperl/bin before /usr/bin

See perlrun, Behind the GUI lives the Shell

Do not be tempted to link /usr/bin/perl to ~/localperl..., you probably don't have permission, and you'll probably break your ubuntu