Can a person who gets a few minor hives from nsaids be ok to take them again if they carefully wean themselves back on them, w a drs help?

NO!: Generally allergic reactions to anything are worse on the second or third exposure and in any event are unpredictable. What caused a minor rash once may cause swelling of the airway and inability to breath or anaphylactic shock another time. While there are methods to train the immune system to become more tolerant of environmental exposers they wont work for ingested (swallowed) drugs.

Drug allergy: Don't try this at home, you are playing with fire. Desensitization can be achieved under strict protocols and under the guidance of an experienced allergist and usually not in an office setting.