Apologies for this.
The contents of this file is simple.
%windir%\Microsoft.NET\Framework64\v2.0.50727\regasm.exe ..\bin\ESB.Core.Async.MSMQTriggersEntryPoint.dll /verbose /codebase %1
Further, if you've got a previous install of ESB.NET 6.x on a PC, this won't have changed.
A patch will be uploaded shortly.
In the mean time, just register the assembly with the command line above.