Chaos feeds of emotion. What emotion do nids have when under the influence of the Hive Mind? None. They have an order issued to them, an imperative that overrides Fear, Hunger or Rage.
Chaos Mutation is as a reward of the chaos gods. It is always a beneficial creation, regardless of how abhorrent it looks, and that slow melding is something that's indirectly come from the will of the chaos gods in thanks for doing something that furthers their goals. This is something that has only been seen within the Human race at large. Other races, Eldar, and Orks for the most part as these two spend quite a bit of time in the warp, have had a noticeable lack of mutation. Tau have their own methods of intragalactic travel (not sure if they have a FTL drive yet though) without delving into the warp, while the other race, the Nids, with their most humanoid and independent creatures, the Genestealers, have yet to show a notable mutation that's not attributed to the Hive Mind creating it.
And even if there was a "warp tyranid" what difference would there be from the Hive Mind/Norn Queens thinking "Those tentacles? I like that shit. Yo, come over here and I sit in my digestive pool so I can learn how to give it all my goons" and it just becomes yet another evolutionary strain rather than an explicit Chaos boon?
In short, nope. Nothing in warhammer 40k current lore supports such an idea. While homebrew is always pretty cool, this is up there with the equally retarded Chaos Grey Knights, and peoples only answer to why they've made them is "because I could", "because I wanted to", or "because it explicitly said i couldn't so because I'm super special snowflake".
100% free webcam site! | Awesome chicks and it is absolutely free! | Watch free live sex cam - easy as 1-2-3