Harken Hoister
We have a Harken Hoister (hoister.com) for our tandem, currently for sale with the bike. I listed the model number in a post to the "anybody looking for one of these" thread. It has been great, lifting the bike equally at both ends and holding it securely.
It connects to the bike with adjustable straps, which we run through the wheels, but you certainly could connect to the saddles or frame. I've done the latter to use the hoist as a work stand.
Hope that helps.
al