If you are running builds locally, make sure all steps that need access to sources and/or derived objects are running on the same machine.
Note: This approach is not acquiring an exclusive resource - it does not ensure anyone else cannot use the resource or potentially interfere with your work. It is your responsibility to make sure another job running at the same time on the same resource will not interfere with your job. You can do this, for example, by creating directories that use the ElectricCommander jobID number as part of the directory name.
Create resources named "windows-1" and "windows-2", or use existing resources. Set each resource as part of a pool named "winBuild".
Create a step near the top of your procedure.
For example, create a step that acquires sources from Perforce.