The best way to get a Juniper checks into the product is to submit an FMR. There is a queue for creating checks and we create the them as fast a possible but we don't have a check for everything. We definitely listen to customer requests though and the more FMR we see for something the quicker it will move up the priority queue.
I was about to create a post asking for the same :-)
Strange that Juniper is not part of vulnerability manager. I hate using multiple products to achive one goal. Please McAfee start with JunOS and ScreenOS support.