...
Set (or add to) the worker_properties value to make a dedicated worker:
worker_properties = "host.dedicated=1"
...or a non-dedicated worker:
worker_properties = "host.dedicated=0"
Via the central qbwrk.conf:
In the [default] section of the qbwrk.conf make all workers non-dedicated:
worker_properties = "host.dedicated=0"
...then, in whatever section of the qbwrk.conf you define the dedicated machines, (or in each dedicated machine's block in the qbwrk.conf), you would set:
worker_properties = "host.dedicated=1"
Then, all your jobs would need to have their "hostorder" value set to "host.dedicated", which will result in workers with "host.dedicated=1" receiving jobs before the non-dedicated machines.