Radagast quests for handicapped players

I am having trouble completing the "Hop to" part of Radagast's Befriending quests. I can do nearly all, but the Calembel cottontail is impossible. I have an old hand impairment and just can't manage to hit the r-click before it jumps away. Is there a keymapping trick I could use (like with my other hand)? Any suggestions appreciated.

Click on the yellow name of the bunny and then just hit 'u'. If you are not close to it, it'll move you close to it and 'u'se it. (Right clicking = 'u'se)

Thank you very much. Very useful tip!