Same question is asked and answered by many programmers on the news group.
Basically simulating a priority queue depends on the simulation tool you are using. One way to model a priority queue is to have separate processes for serving the queue and for inserting customers into the queue. Customers may simply enter the queue at the end. Customers depart automatically when it is their turn and this departure time, of course, depends upon the dynamic behavior of the model. Many other simulation tools force artificial structures on the model, requiring the job to be moulded to the tool.