Take route 302 West from Bartlett. Park at a pull-out on the right (across from the pull-out for Willie's Slide winter ice climb) about 1/2 - 3/4 mile beyond the Willy House. The usual approach from the pull out is to walk back towards Willy House on the road about 0.1 -0.2 Mi (I recently counted 130 guard-rail posts from the parking pull-out.) Just beyond the large-diameter birch, look for a cairn on the road-side (about 15 ft "down slope").  Cross the Saco here (bring water-crossing shoes if at all high), then walk left (upstream) on a sandy bar for 40-50 +/- ft ( crossing a small stream) Look for a 12" diameter, downed silver birch tree (maybe with a cairn on it) to pick up the climber's path [Photo] (orange flagging, cairns) that leads south (i.e. up and to the right) to the big watercourse/gully. Follow this steeply uphill (at a blowdown look for the path on the right that goes around the blowdown and then comes back into the gully) to the base of the slab and start of the climb "Lost in the Sun". About 45-60 Min. When ascending, "memorize" where the path leaves the gully to return to your car. It's cairned, but not THAT obvious.

If the Saco is too deep to comfortably wade across, go back and take a look at the slab...it's probably too wet to enjoyably climb! 

A COMMENT has been posted to the effect that one can hike by parking at the Willey House, walking west ("up-notch" toward Mt Willard) to mile-marker 45.6 (on left side of road), going 2 more "white markers" (on right side of road) and heading down and across the river, and straight up the slope on the other side. I think this is a bit further of a walk on the road.