1. Walk from the Four Queens towards Downtown Grand. Just before you cross Ogden, turn right. There's a stop just before 4th Street.
2. Catch the Boulder Highway Express towards Henderson. It runs every 10-12 minutes during the day.
3. 30 minutes later, right after passing under US95, you'll be at a stop right across from Boulder Station's big sign. Get off.
4. With your life in your hand, cross Boulder Highway to the casino.
I've done this, it works just fine. Good luck!