How to install Fedora&Ubuntu with encrypted VG's on one disk?

[johhny_at_poland77]

I installed Fedora 14 first, then Ubuntu 10.04. I installed them using 
dm_crypt/aes256/lvm, so I used encrypted VolumeGroups. At the end of the Ubuntu 
install it said it cannot install GRUB, so I had to use SuperGRUBdisk to start 
Fedora and give the command:

# grub-install /dev/sda
Now I can boot to Fedora normally, without using supergrubdisk, but the problem 
is, I can't boot to Ubuntu!

Is there any working way to install Fedora 14 & Ubuntu 10.04 using (separated) 
encrypted VolumeGroups (each volumegroup with other password)? Such that 2 
users (who knows the root passwords of their own distro) can use 1 PC but not 
see each other's files?

Can anybody help me? I'm searching for the answer "for ages" now...