I think you could just save that particular file as ExtDBH.pm in your perl/site/lib folder.

In general, it is not a good idea to install modules in that way (mainly because it often doesn't work) - but it looks to me that it should be ok in this particular instance.

ExtDBH.pm uses the module 'UserException' which is not to be found on CPAN. If you want ExtDBH.pm to be usable you'll also need to track down UserException and install it as well.

Cheers,
Rob