There are examples of ASM installations in my RAC articles:http://www.oracle-base.com/articles/rac ... es-rac.php
They show you the necessary steps in both Linux and Windows environments. They are using virtual hard disks, so you can ignore the VM setup parts, but the operations necessary on the disks once they are presented to the host are the same.
Remember, if you are using ASM for RAC, the disks *must* be on some form of shared storage. They can not be local to the machine. In the articles I used virtualization to create virtual shared storage, accessed by multiple VMs.