Whether you wear Uggs or slinky sexy high heeled boots with your jeans, it's not easy to get the boots on over your jeans and keep your jeans in your boots.
Most people I know end up using the old sweat sock method. Wrap your jeans around your legs and then pull your sweat sock up over them. I have a couple of problems with this method. I find it uncomfortable and not very effective. I think the jeans look a little weird wrapped and they definitely feel uncomfortable to me. I also don't think that socks keep the jeans in the boot as you move around.