Problems installing Mountain Lion

So I tried to install Mountain Lion on a system running 10.6.8 while having a boot camp partition on the computer. I received an error message similar to the one described on http://support.apple.com/kb/HT4649

However, I do not have a large enough backup drive to completely time machine back up my entire device. I was able to back up the boot camp partition and all of my personal files, but not everything or applications, so I really am not jazzed about the idea of completely erasing my harddrive and the attempting the installation of all software from scratch. Since I could backup the boot camp partition I did so and then removed the partition from my device. Now when running the bootcamp installer it simply tells me that my disk cannot be used to start up the computer. Otherwise my computer is working fine. Any thoughts anyone of how to fix this short of reformating my entire drive?