You mean like this?
I shattered my right shoulder during a race at Sears Point, and after the surgical reconstruction it was in an immobilizing splint on my right side. Looking at six weeks before the splint would even come off I bought a Helix 250 and the Armec Tremolino rig painted in the Honda red to match the Helix.
Assembly was straight forward. Bracket assembly clamped (think triple clamp) to the bottom of the two frame tubes in four spots. The sidecar frame then slid into this bracket assembly and was held in place by two large hex cap bolts on the left side of the bracket. No brake on the rig wheel, and simple torsion bar suspension.
Since I had no use of my right arm for a while I stripped the housing off of the stock helix 'bars' installed the throttle assembly on the left grip, and flipped the cables at the carb. I dropped on a clutch master cylinder from a Superhawk and used it to work the front brake.
The rig was super light, and would cruise 70 on the highway comfortably all day long. The only problem I ever had with it was shattering a rear rim with lateral loads railing around the twisties up in the Santa Cruz Mtns. A problem easily and inexpensively solved replacing the cast rear rim with an older used stamped steel rim.
Best thing about it was once my shoulder was healed and I flipped the controls back over to the right grip... I could hop in the tub and bomb around driving from the hack with nobody riding the Helix. I even eventually learned how to fly it while sitting in the tub.
It was a beautiful rig, and my first sidecar. I do miss it... but I sold it to a fellow club member when he shattered his femur.