I sit in a big lazy boy type rocking chair/recliner. I don't recline it though. I lean forward. My feet are on the ground but up on the toes. Right elbow on right knee. Left elbow on left knee. I hold the nunchuck in my left hand and sort of cross it over my right hand to help steady my aim (my hands are too twitchy to aim with one hand).
If I'm playing with a regular controller I'm normally curled up in the chair and leaning on the left arm rest.