not sure if this is the best technique, but one i observed very early in my student clinicals at a nursing home in the alzheimer ward, is the cna would weekly (as it was the policy every resident showers at least once a week there), would trick this lady into getting a shower, each week i understood she would use a different tactic.
the week i observed it, is as the lady was going to use the restroom, the cna ran across the room, and shouted, "don't use that toliet its broken!", then proceeded to guide the lady to the shower room saying, "here the toliet in here works, let's use this one." then while the lady was doing her buisiness (they had an arangement with the shower chair rolling directly over the toliet which the cna placed her on) the cna helped her undress and then said, "we'll since we're here in the shower room, and all ready to shower, lets shower!"
after a quick shower the lady emerged smelling much nicer, however did little to improve her mood as i believe the comment was as follows, "i'm going to shove my foot up your ......" probably well deserved, but as i understood it, that particular cna and that resident had a unique relation of being each others arch nemesis. dunno, hope this helps.