It, and its fellow Animechs, are now for sale at the Rebel Miniatures website.
Here's the link- http://rebelminis.com/animechs.html
There are several other ways, of course, but this seems to be the one that's worked for me on various multi-leg mecha builds.
This same method also works on assembling the legs on the SpiderMech.
Let's get started...
You can insert any of the close combat weapon into the socket at the tip of the tail, or a special weapons module that has a number of weapon sockets on it.
The Animechs were designed with modularity in mind. Dive deep into those bitz boxes, and come up with some cool combos.
Edit to add:
I mention the tail weapons mount, but don't show it until the final pic. Here's the details...
There's a ball stud at a diagonal angle at the rear of the mount. This mates to the tail socket.
Don't use the one that's looking forward, like a sensor eye.
Again, they're now on sale, so pick some up, and then come back and here figure out how to put them together.