You can try. The problem is making sure that the Realtors KNOW about your open house. Normally, when we run a Broker's Open... we publish the dates/times in the MLS, so all the agents see it.
Make sure you take flyers to local agencies, to make sure agents know about your Broker's Open. (Don't go too early... we don't have a long attention span)... if normal Broker's Tours are on Tuesdays in your area... make sure the flyers are there on the Sunday prior.
You may want to offer "finger-food" (donut holes, danish, bottled water... that sort of thing)
Now... assuming you're successful... what are you going to do... hire an agent based on their personality at the open?? Just because someone dressed nicely, or spoke to you kindly, or complimented your decorating does not make them the "right" agent to list your home.