1. A method, comprising: a) automatically delivering an electrical signal to a cranial nerve of a patient according to at least a first parameter and a second parameter; b) automatically measuring an electrical response of the nerve to the electrical signal; c) automatically adjusting the first parameter while keeping the second parameter at a first test setting; d) automatically repeating operations a) through c) to acquire a first plurality of electrical responses; e) determining a lower threshold for the first parameter with the second parameter at the first test setting and an upper threshold for the first parameter with the second parameter at the first test setting, based on the first plurality of electrical responses, wherein the upper threshold corresponds to an electrical signal level above which increasing the first parameter does not cause a significant increase in the electrical response; automatically adjusting the second parameter to at least one different test setting and then automatically repeating operations (a) through (e) to determine lower and upper thresholds for the first parameter with the second parameter at the different test setting; recording the determined lower and upper thresholds and the corresponding test settings for the first and second parameters; determining customized treatment parameters for the patient, based on the recorded information; and programming an implantable medical device (IMD) for the patient to treat the patient according to the customized treatment parameters.