You can most definitely use the pliers to crimp the pins. As for the strength needed, I'm guessing you were trying to get the crimp with pure force rather than using a "technique". There are two ways I accomplish this:
The first involves using the pliers in the same plane as the rail and compressing into the pins groove:
The second way is to use the pliers like you would be reforming the rail, but get an end right at the groove on the pin and give it a gentle twist each direction.
As for tightening the tie on the rail, a hammer, punch and backing will be all you need. Since my punch set came with multiple punches, I use one of them for my backing as it fits in the recess of the tie.
