squeaky poly bushings driving me nuts, ideas?

A while back when I did my bushings some people suggested installing a zerk/grease fitting into the leaf spring. I did not do this mostly because I was not pulling the entire rear end. I like the vegetable oil idea but the bushings are TIGHT I am not sure how you would get it in there. I used a synthetic grease for suspension on mine and my passenger side has a light squeek but not bad at all.