webserver60 is a provider and not the computer name. You can read more about providers here. So if you are syncing from COMP1 to COMP2 and you are running this command from some other system (not one of these) then you would do it as follows:
msdeploy -verb:sync -source:webserver60,computername=COMP1,username=<yourusername>,password=<yourpassword> -dest:auto,computername=COMP2,username=<yourusername>,password=<yourpassword>
If you are logged in a user that has admin permissions on COMP1 and COMP2 then you dont need to specify the username and password.
You either have to install msdeploy on all those servers and start the msdepsvc agent or if you dont have msdeploy installed on those servers then you dont need to and you can use tempAgent switch as follows: [As long as you have WMI allowed thru the firewall on those boxes]
msdeploy -verb:sync -source:webserver60,computername=COMP1,tempAgent=true -dest:auto,computername=COMP2,tempAgent=true
Let us know if you need more information.