The c-clamp tool is a PITA to use. I bought the same balljoint tool that baum sells but for 1/3rd of the price.
BMW E38/E39/E52/E53/E60/E61 Rear Axles Bush Removal Installer Bushing Tool | eBay
Make quick work of the rear balljoints. Pushed the old ones out and the new ones in like it was nothing. I bought it after struggling through removing one side with the c-clamp.
I'd be willing to loan it out if someone doesn't feel like buying it.