Buy a stainless steel ring, 2-3" inches in diameter. Take the jib sheet out of the jib and lay it double. Thread the doubled middle of the sheet through the clew. (It's hard, but should be possible. If it's impossible, your sheets are too fat and should be replaced anyway.) Slip the ring over the doubled end of the sheet. Thread the ends of the sheet through the doubled end, one on each side of the ring. Got that? (This is a test.) Pull it tight. Now you can snap the pole to the ring.
Another method: instead of attaching the sheet directly to the jib, tie a short length of small-diameter, STRONG line between the center of the jibsheet and the jib cringle. Then clip the whisker pole to the small line. The only problem: the knots in the small line get pretty hard, but I leave my jib sheet attached all the time anyway. On the rare occasions when I need to undo it, a pair of pliers handles it with no sweat.
I used hi-tech line â€“ Spectra or Vectran or some such â€“ about 3/32 inch diameter. Plenty strong enough, but inspect every so often to make it isnâ€™t being cut.
Tie a small loop in one end of the small line using a bowline, wrap the loop around the middle of the jibsheet, pass the free end of the small line through the loop and pull tight. The arrangement tends to pull the middle of the jibsheet into a small bight which is good.
Tie the other end of the small line to the jib clew with a bowline. Leave about 3 inches of small line between the clew and the jibsheet.. I leave my jibsheet attached to the jib, so taking out the knots each time I sail is not an issue.
The arrangement has never slipped on me, but if it does or youâ€™re concerned you can tie a knot or loop in the middle of the jibsheet. Hope this helps