You just have to tell your browser to open the particular content type (text/plain with gvim, or a g?vim? in a terminal emulator egxterm -e vim. Opera will all you to do all manner of silly things with content types it doesn't know internally, such as passing the uri/downloaded version/filenames to another program etc...
I'm pretty sure the only thing you could do at PM's side to help this is by allowing the user to select the Content-Type header sent with code downloads, allowing the user to specify a header of text/x-vim, or perhaps a type perlish, so windows users get it going to their perl editor instead of their regular text editor (which most likely defaults to notepad)
@_=qw; ask f00li5h to appear and remain for a moment of pretend better than a lifetime;;s;;@_[map hex,split'',B204316D8C2A4516DE];;y/05/os/&print;