I do not know that it is possible to add devices by hostname only, I know in 9.4.x McAfee removed the field for WMI netbios name, but I believe you still need the IP address.
I would consider doing an ePO deployment of the Windows Event Collector to the workstations, and using the client machines host-name as the host-id in the configuration. In the receiver interface, communications tab, you can specify the DHCP range to listen for MEF, and then on the host machines you are creating data sources for, do data retrieval method MEF, and specify a name and host id.
As long as the host id is correct and matches the host id of the endpoint configuration, you should be able to place your data into appropriate containers.
Not sure if this is still an issue for you but I got it going using the FQDN name (pc1.contoso.com) versus just the hostname (pc1). Hope this helps.