These docs are for an old release.
Info on upgrading to v6
Event::setResources
Sets the Resources associated with the given event.
event.setResource([ resource0, resource1… ])
Can accept an array of resource IDs:
var event = calendar.getEventById('1');
event.setResources([ 'a' ]); // set a single resource
event.setResources([ 'a', 'b' ]); // set multiple
Can also accept an array of Resource Objects:
var resourceA = calendar.getResourceById('a');
var resourceB = calendar.getResourceById('b');
var event = calendar.getEventById('1');
event.setResources([ resourceA, resourceB ]);