If you're coming in at night, best to check in at Chief Will-Yum campsite for the night, as the alternatives are hard to find in the dark. Hit the Gecko Tree for breakfast first thing, then to Red Shreds if you don't have a trail map already. Since you're shuttling, leave one truck at the shop as you'll end up just down the road. Day 1 will be taking you to the Westsyde network for some of the bigger lines.
Drive to Highway 20 and begin heading up the hill. At the corner store on your right turn on to Hodgeson Road. Stay on this road all the way through the S curves and past Bell-E-Acres golf course. Turn right on Bysak Road, which is the first right you see after the golf course (You'll see a blue and white MTB sign). Drive under to Power lines and along this main road staying left until you see the Kiosk ad Trail Head. You'll be starting on Snakes and Ladders which was re-built in 2012. Wuth 22,000 board feet of lumber, the jumps, log rides and stunts of Snakes will keen you stoked for weeks. The trail is well signed and once at the River Valley turn right and pedal back to Mackenzie along the road. Shuttle up and hit it again, I would think.....
Another option for your first day is Back Door. You'll need to set up the shuttle in the second parking lot in the river valley. To get there go towards the dump along Mackenzie, then turn left onto the Soda Creek Road, then left again immediately and cross the rail tracks. Turn right and take a road just on the left side of the recycling depot. You'll get to the bottom, cross a bridge then head right till the parking lot. Once you've dropped the shuttle, head back up to Snakes.
This starts just off Snakes about 300 meters in on your left. You'll need to pedal to the top whcih will take about 30 minutes, but its flowy and there are some nice stunts along the way. Once you get to the top of the rock pile, there are two jumps and its game on to the river valley.
Hope your day one was good.
Your day 2 will take you to Desous Mountain West of Williams Lake. You can load up the truck with provisions for camping as you'll be able to stay out there. Take lots of water as there is nothing fresh. You'll head up Hwy 20, and if you're planning to shuttle the backside, go all the way to the Sheep Creek bridge and right before it on the left you'll drop a truck on English Road about 2km in. There are signs for the shuttle pick up points of all the trails, so start with Soo Long.
You'll drive back towards town and turn right on Dog Creek Road. You'll take this road for about 1/2 hour then eventually see Desous Mt. Road on your right. Head down this road for about 2.5km and take a right. You'll cross a cattel guard and start heading up to the top. You'll pass a red gate and you know you're in the right zone. this is the start of the shuttle road all the way to the top. It's a 40 minutes push to the top if you want to hit a front side before you drop onto the back.
There are three main lines to the Fraser - about 3000ft of verticle. We suggest starting with Soo Long wihch starts just in front of where you'll park at the old fire tower. The second line we suggest is Prime and Endless, which is awesome, and ends in some super steep corners back to English Road. If you have more in you, and are willing to man up - try God Speed - whcih is intense for sure.
Be sure to pack out your trash and enjoy!