I have written previously about running CentOS on Hyper-V. Subsequently, I updated my VM from CentOS 6.2 to 6.3. When this happened the kernel version changed to 2.6.32 and the drivers that used to support the Hyper-V virtual hardware components do not work. Microsoft has released a newer version of LIC that works with the new kernels. You can get the newest version (as of the writing of this post) here:
I ran into another problem which was when I inserted the ISO, the CD Rom device was not present inside the VM. This is because the MS components install their own ATA driver for the synthetic IDE disks. You can insert the original kernel module in order to mount the CDROM.
insmod /lib/modules/kernel-/kernel/drivers/ata_piix mount /dev/cdrom /media
The ATA driver issue is discussed in http://support.microsoft.com/kb/2600152.