This doesn't address the original query, but it's what I do for the tech challenged, and they're not all elderly.
I pre-set up Ancestry.com user name accounts. I've then "invite" those user names accounts to view my tree. I also set up home pages, making it easy for those I give those user names to sign into the site, and find my tree.
This has worked really well for the people you'd like to give access to see your tree, but will never figure it out on their own.
All you have to do is send them an email with the hyperlink to ancestry.com, give them the user name and password you set up, tell them where to put that info in (two boxes on the upper right of the page) and hit "sign in".
If they happen to sign off and get can't remember how to, I just resend the email.