So this is probably completly silly and too over the top. But I was thinking wouldn't it be cool to crate a rough rider stile regiment that is sort of like "Dino Riders"?

Something like this picture:

http://2.bp.blogspot.com/-4hjoQTV4V9c/UEmxdtTqW_I/AAAAAAAAACE/CMjOJN7N41w/s1600/Krulos.jpg

Would it be completely against 40 k lore or is that somethign like that could a actually exist there?

Can we simulate that with only war regiment creation rulles? There is a way to design mounts. But I am not sure how would one go about putting heavy weapon platforms on them.

Well, 40k lore being the way it is, anything is possible, as long as it is grimdark and all. Dinos as mounts sounds very deathworld-y and I would allow it for sure. Depends on how big you want them, but you could easily build them in HotE's mount creation system.

As for the heavy weapons platforms, that gets a little bit trickier. RAW, there is no way to make a mount with heavy weapons mounted on them. The mounts presented are more along the lines of traditional horse cavalry, as opposed to elephant corps (which is kind of what you are looking for).

However, there are examples of creatures with weapons on them usable by riders, and the regimental (and mount) creation system was meant to be broken.

The first example is that of the Squiggoth, a massive Ork-elephant thing that has a "howdah" on it. This is essentially a gun nest with a bunch of heavy weapons on it, comparable to how elephants were sometimes used in real life, or how the Mumakil in Lord of the Rings was. This creature would have a handful of soldiers manning the heavy weapons, with a driver.

On the other hand, you have the Krootox and Great Knarloc, both Kroot creatures. These are large beasts that have one rider, and the option of a weapons platform. I imagine that this is what you were looking for, going off of your picture.

So, I would rule it as this: you design the mount you want, and just incorporate the "weapons platform" from the Krootox and Great Knarloc, probably with a point cost of 2 to balance it all out.

HotE mounts, Unnatural Strength and Toughness, high strength and toughness, nasty bite...

Pretty much puts you there. Compare Mukaali, HotE, p. 140.

The only trait you're going to be missing is auto-stabilized/weapons platform (as mentioned above) - and having your GM sign off on it, ofcourse.

Thanks a lot for your input guys. It was helpful and gave me some good info/ideas.