Place all ingredients in slow cooker, except for lime juice.
Heat on high setting for one hour, then reduce to low. Allow to cook 6 - 8 hours, until completely done.
Use fork to shred meat and incorporate liquid.
Add lime juice, continue to mix.
Serve hot and top with cheese.
Notes
Heat a tablespoon or two of olive oil in saute pan over medium high heat, place buns, crust side up in pan to gently brown and crisp them before serving. Consider adding 1/2 cup chopped fresh cilantro