I use two pair of pliers: first is a cheapie needle-nose, second is a smaller vice grip. I will also use the Hobie tool, (aluminum, ask your Dealer), and a home made tightener made of two 3" lag bolts, 2 1/2" apart, screwed into a 2" x 4" offcut about a foot long.
Thread the line fairly loosely, snug up by hand, then go to work. Working grommet by grommet, grab with with vice grip and PULL, then with your free hand, jam the needle part of the needle nose into the grommet hole so the line does not budge, and move onto the next hole. Keep the line tight and repeat the process.
The Hobie tool and the home made tool allow one to 'twist' the line, then pull on the free end so as to snug it even tighter.
Just think of the joy of doing this at least twice during the season....but do remember, it's what holds your Hobie together.
1989 Hobie SX18 Sail # 1947
'Only two things are infinite, the universe, and human stupidity. But I'm not sure about the former.'