Being the Molift rep in central north.. I do this all the time and have got it down to an art! That said it does take some practice. One wants to hook the static side of the strap on quite close to the unit so that by the end of the move there inst heaps of belt run through the sliding sleeve to the other side. That closer hook on the static side keeps you as the helper closer to the whole situation by the end of the move.
Also it is possible to have the strap without the sliding sleeve which I think is not making the best of it. One really wants to two parts to work together to get it all to run smooth for assisted standing.
There is a new belt and raiser (the pro) only just on the market. It is featured in the link above that you posted. I don’t think its in CHCH yet…. The belt can make a good difference in terms of the user feeling a bit more secure (it buckles and has a wide non slip fabric) and one wont have to have a separate sleeve and strap as its all intergrated. I think its better. The belt is to guide movement, initiate really and then on the way down to control if things are getting a bit wild in terms of touch down speed.
I know the CHCH Molift rep Ian would happily show you the how to on the new gear if you wanted to get hands on with it.