Enter from Arlington Heights. You will see a sign that says "Main Dam" which is south of Golf Rd.
From where you parked on the map, head down the bike/walk trail all way across the dam bridge. Make your way down the creek on the west side of the dam and you run into a short creek that leads to the WWD. You'll see the tunnel. Good luck!
I parked in that neighborhood about 10 years ago, but it was only for about an hour. I've heard that some people park have parked there but I wouldn't really recommend it. Parking on side streets in suburbs can have lots of restrictions and they usually tow in a heartbeat.
The next WCF podcast is in the works and will have information about fishing the Busse warm water discharge so stay tuned.