Cloudmin, Centos, LVM, ext4 image?

I am running cloudmin GPL and the only machine images I see are Centos 6 with ext3 (with or without Virtualmin).

Centos 6 should now be using ext4. When using LVM as the underlying file system, I believe the same advantages to using ext4 on a non VM system apply.

Is there a way to make a new kvm machine using ext4 filesystem when using LVM? I realize this may not matter when using disk images, but, I am using KVM.

It requires building your own image file based on the instructions in the doc.