simple pointers would be like this:
1) upload iso and set up image file for linux starting with size of 5GB or up
2)*this step is optional* create virtual machine with guest os kernel and inird (it can retrieve them from image, but to make sure you are using same initrd and kernel that os uses do that)
3) set up VNC port to connect to your guest.
after this, you should be able to follow simple linux installation procedure to install it.
I can install CentOS5.8 just fine on a KVM, but 6.x won't install at all. The same thing happened to me for Ubuntu, I was able to do a dist-upgrade from 10.04 to the latest. Is this a known issue? Is there a work around for it? I was running 5.20 and 5.21.