How would I get tested for an allergy to wheat?

Depends on symptoms. An allergist can help you figure out what tests are best depending on your symptoms. There are many kinds of wheat reactions: allergy, gluten intolerance, and other wheat intolerances. Different tests are used for each. Most are blood tests, but sometimes a wheat challenge is necessary to determine what is going on.
Many options. The best ways to test for wheat allergy are skin testing and blood testing. Both methods are effective, both should be ordered by a board-certified allergist. Blood testing is looking for ige to wheat--many doctors are now ordering igg to various foods, but these tests are not valid/reliable.