If you want some made-up rules for Alienhunters, Issue One of The Inquisitor, 40kterra.com's online magazine, has an Alienhunters "Chapter Approved"-type thing that I wrote. It has 4 other good articles, too!
http://www.40kterra.com/inquisitor/Issue_1/index.html
Just to make sure I'm clear, these rules are in no way approved or toruney legal. They are also in no way a sort of "sneak peek" for the actual Alienhunters codex. I have no idea what will be in it except for Inquisitors and Deathwatch. And probably Inquisitorial Stormtroopers, becuase they're in DH and WH, too.
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Lord of Fluff and Blood Angels
Herald of Nurgle
"I wield my power with the Emperor's Authority. Those who would say that I am 'radical' merely have minds too small and impotent to realize all the weapons at their disposal. Do not question my methods on account of these so-called 'Puritans'."
-Inquisitor Mathias Rosenadel