I wrapped my friend's MSP's rear sway bar with teflon tape before re-installing the OEM bushings, it has completely eliminated the squeak. Previously we tried all kinds of grease to no avail, so give it a shot and let me know how it goes!
I will warn you though, get the quality ones from Lowes/Home Depot and not the $0.99 package from Advance Auto. I've had problems with my fittings leaking because the el cheapo Advance tape was super thin and sucked.

I will warn you though, get the quality ones from Lowes/Home Depot and not the $0.99 package from Advance Auto. I've had problems with my fittings leaking because the el cheapo Advance tape was super thin and sucked.