Removing the crank pulley is not very easy. I don't recommend even trying by yourself in your home garage, unless you've got friends to help and/or the right tools. The best tool for locking the flywheel in place would be to order the one that Nissan lists in their service manual, but you can get by with a second person and a prybar or large screwdriver to hold the back. Get the biggest longest breaker bar setup you can for loosening the front pulley nut.
First paragraph from my stillen pulley install here might prove useful:
wstar's Journal