I've always found getting the first bead into place is relatively simple - the problems for me are more getting a folding tyre to stay in one place given I only have two hands to hold it.
The second bead can range from tricky to all but impossible. I used exclusively Marathon Plus tyres for a good couple of years and they were a devil to get on - in the end I used levers to get the last 12" or so onto the rim because my thumbs just weren't strong enough. When I got a flat I did the same. Then when I swapped them for Durano Plus tyres I had the exact same issue and used the levers again for the last 10-12".
When one of my tubes had a very slow leak in it I re-read my book on bike maintenance and it said to start putting the tyre on opposite the valve and work towards the valve (I'd remembered it the wrong way around, and started at the valve). Doing it that way made it much easier and meant I could get both beads on with my hands.
Using levers to get the tyres on isn't ideal but I've done it probably half a dozen times and never pinch-flatted anything so far.
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