Stem plants are a pain in the butt (another reason I don't have any in my 75, besides the fact that I'm a perfectly proportioned 5'1" and the rim of the tank is a tight squeeze in my armpit).
What I use is a salad fork (or is it the spoon) to sort of scoop out a pit, then use my kent algae scraper to push the gravel back over the roots of the plant that I'm holding in place with my elcheapo tongs.
It's so much easier to plant a tank that's below armpit level and shallow to boot. I can use my hands for that.
If you're doing a new set-up, what you can do is reserve half the substrate and add it around the plants as you go (it's a gardener's trick - fill the pot half full, put the plant in, and add more to fill it up. Easier than filling the pot full and trying to displace soil for a rootball)
My mind is aglow with trancient nodes of thought, careening through a cosmic vapor of invention - Hedley Lamar