In order to do a graphical install (which lets you customize your LVM volumes) you just need to add the vnc option to the "OS Boot Parameters" when creating the VM. It should look like this:

view plain print about
1graphical utf8 vnc

Once you start up your VM, it will go through a short text based configuration wizard, configuring your NIC and such, after which it will prompt you to log in using VNC.