I have got the parts, and installed them, and the boom works!!!
Most importantly, it looks awesome and not a single significant modification was made to the Lama or the boom!
Here are the pics:
-All 4 mounting holes on the boom had to be widened slightly, the upper ones to accept the canopy mounting rod, and the lower ones to attach to the main-frame. Widening can be done gently with a small screwdriver, as the plastic stretches quite easily without actually drilling.
1. Remove both the canopy pieces from the Lama V4
2. Assemble boom, slightly enlarging the top mounting holes on the boom to fit the canopy mounting rod.
3. Unscrew the battery holder (4 screws) and move to side
4. Extending from the bottom of the Lama's frame will be 4 posts that had the screws from (3) entering them to hold the battery holder.
5. Enlarge the lower mounts on the Xtreme boom to fit neatly around the rear two of these posts.
6. Push the lower boom mounts over the rear posts, the top hole on the boom will now match up with the top canopy mount on the lama.
7. Re-attach the battery holder with the 4 screws, this should hold the Xtreme boom's lower mount in place.
8. Re-attach the canopy, the top canopy mounting rod will hold the boom's upper mounts perfectly.
Applaude yourself, and settle down for a contragulatory beer.
Or if not drinking, trim the heli slightly forward, and test it out. I found that the easiest way to account for most of the boom's weight is to move the 4in1 nearer to the front of the heli.
Sorry for the rubbish photo quality, if someone wants to take better one's with a proper camera when they try this out, be my guest!