We don't know who the Wizards opponent will be in their US Open Cup qualifying match is yet, but we do know what location the Wizards are using in their bid to host the game. Buried in an article about an Olathe School Board meeting (Thanks to KC Soccer Review), is a note that the district agreed in principal with the Wizards for the College Boulevard Athletic Complex to be the site of the Wizards match on June 4. The deal is pending a formal approval by the district and the Wizards.
I would assume that this is not for sure the site of the game yet. Team's in the US Open Cup bid to the USSF to host the game. So the Wizards and CBAC will be going up against Dick Sporting Goods Park (Colorado) and the Home Depot Center (LA) for the chance to host this qualifier.
The Wizards will face the winner of the Rapids and the Galaxy, who meet May 27th in LA.