It will take time, but the community will start to change, and thus actually change what users are searching for.
Think of HTML/CSS. One gets a more relevant set of results by searching HTML5, because there was a great deal of effort put into explaining how the language had changed. When looking for bleeding-edge features, a search for CSS3 is more helpful than a search on CSS (which like the perl situation, sometimes returns legacy garbage). The same applies when trying to troubleshoot a problem on OS X: adding 'lion' to the query often improves relevance of results.
I short, make a conscious effort to create a new label and inject it into the public consciousness.
You can resist it, as has happened in various communities (i.e. python) but to actually compete with perl 6 and try and make the two different languages is down-right cult behavior. Perl isn't a person, it doesn't have feelings. If you tell it "screw you perl 5, perl 6 is better" it's not going to cry or leave angry messages on your phone. It's just a tool.
And well, with the pace Perl 6 is moving on it'll be another decade for it to become production-usable. There may be only 5% of the feature-set missing (maybe more, maybe less, i don't keep track), but those 5% are the hardest part, and then comes the task of making all that run fast and to bundle it up, etc. etc. I wouldn't hold my breath. Also see chromatic's writings on that matter:
http://www.modernperlbooks.com/cgi-bin/mt/mt-search.cgi?blog...
http://www.modernperlbooks.com/mt/2011/08/why-my-side-projec...
And if it's truly a different language then you should change the name. Racket did it. And then you would have room to eventually have a version 6 of perl (what you call perl5 now).
And well, it is usable as in, you can write software with it. It's just not commercially usable or complete.
My point was that OP complains they can't change what users are searching for. I assert they can, but they have to change the way they market and talk about their language. They need to present it as markedly different and give users a way to differentiate it in search from previous versions.
(Aside: I don't use Perl. I don't want to use Perl. The things I need to get done I can accomplish in other languages, and that are clear when I look at the code six months later.)