a.) Not sure why you're trying to install grub to /dev/sda1 when the part mounted at root is

/host/ubuntu/disks/root.disk

b.) Not sure why you didn't mention this whole time that you were talking about a Wubi install and not a normal install...

c.) Now that I see you are working with a Wubi install and not a regular install into an actual partition on an actual hard drive. I can tell you that what you are trying to do will never work. Since your "install" is just a regular file within another partition, Chameleon will not bother with it.