Does anyone know of a good intervention to do with a patient you has hemiplegia, severely limited AROM in all areas, and needs to increase his independence with upper extremity dressing?

Have you tried changing the surface level?  Having the client stand up to pick something up from off the table or pick something up from off of the floor in sitting is good, as a start (they could also release a 1-2# wt onto the floor).  Also, stabilizing an object at the top, by the therapist, and then having the client attempt to grasp various sized objects is good.  Have you tried any force modulation?  Also, you can have the client hold onto a dowel rod, with both hands, and have the client do a crossover pattern (like a grapevine). 

Have you tried a cone, finger separator splint or a type of volar resting hand splint?  If she is only contracted in the hand, and not the wrist, that is a bit odd.  However, everyone is different! 

If it is just in the hand, the cone splint can be introduced for a minimal period of time per day to progress to a longer wear schedule or nighttime wearing.  If there is increased tightness or contracture in the wrist, you may want to look into volar splinting options that include the hand/wrist/forearm.  This will increase support and address the hand contracture.

Any type of splint you introduce will need to be complemented with a good preparatory program, rom/exercise program, pt/nursing education, among other areas.  I would talk to your supervising COTA or OTR and ask their thoughts as well. 

Good luck!