In order to netboot an Alpha, you will need the following: (You can also do this via MOP if you're a weird vms person, but I've absolutely no idea how)

Enter the srm console. Type show device in order to get a list of devices. Any ethernet devices will have their MAC addresses printed next to them - use this in your bootp server configuration. For older Alphas, start a bootp boot by typing boot ez0. For newer Alphas, try boot ewa0. If it tries a MOP boot, do boot -protocols bootp ewa0. The system will then bootp, tftp a file off the tftp server, run it and mount an NFS filesystem as specified in the bootp server configuration.