Jen:
I have dug out overgrown Yews and Junipers a couple times. Junipers are more of a pain because they are prickly. My method involved getting in there and digging them out by hand. I cut the main branches off with loppers and then dug out the majority of the root ball. I have not had any problems with them growing back. A mattock (a heavy tool with a digging axe and pick axe) is pretty good at chopping through roots, and it is helpful if the ground is moist but not muddy.
This may be more physical work than you are up to...I note your profile page mentions a bum back. Maybe you could hire some laborers or some friends to help out. If you try to pull them out with a car, be sure to tape it. I love watching those segments on America's Funniest Home Videos where either the hook or the shrub flings up and breaks out the car window. ;-)
- Brent
Q
Pick mattox
Q