Yes, this is definately possible and is one of the more popular ways to instrument auto-scaling
First, instrument monitoring of a particular queue or queues by monitoring the Azure resource that the queue is located in. Instrument monitoring of the AzureStorageQueueLength or the AzureServiceBusActiveMessageCount metrics within their particular resources.
Second, link the monitored metric to a particular monitored cloud service via LinkedMetric metric. This will import monitored data from one resource to another.
Third, instrument your scaling rules using the newly defined Linked metric.