The short answer is to buy the appropriate size BVM "Tire Change Tool" and save yourself a lot of aggravation. If however, you want to risk the frustration, try this;

Warm up the tire in hot water. Oil up the rims and start working the tire onto the rim. Wedge in popsicle sticks as you go and use as much downward pressure as you can apply, up to and including standing on the tire (a helper can be useful here). When all this does not work, refer to the short answer above.

Craig