From Los Angeles County:
10 Eastbound until you hit the 8th Street-Highway 243 exit at Banning. Exit South to Idyllwild. Follow it up the mountain and keep going. You go through Pine Cove and then you will wind up in Idyllwild.
60 East until you reach Gilman Springs exit and turn right. This will eventually run you into an intersection at Sanderson Road. Turn right. Make a left on Ramona Expressway. Follow this until it ends on Florida (the main road in Hemet). Make a left. You will now be going toward the mountains on Highway 74. Follow 74 until you run into 243 toward Idyllwild & Banning which is a left-curving exit on the road. 20 minutes more and you are in town.