I think your best bet is to take the Lilly Lake approach. Follow the Lilly Lake trail for a few miles while it meanders up into the basin (S/SW) and gains some altitude. There is an obvious point in the trail where it starts to head N/NW and up to Lily Lake. At this point you leave the trail basically bushwack and talus up up to the base of the actual cliffs. You can get a good view of the rest of the approach from here as well since you will be standing in a bit of a clearing. I believe you should be able to follow this all the way around to the gash. There isn't a trail past the point where you turn off.
I haven't climbed the gash but we attempted Ormes Buttress last summer and this is how we went. It was pretty straight forward, albeit a slog across the talus. In March/April you will want to watch the snow slopes when crossing what was talus when we were there in August. They aren't too steep, but steep enough to slide and if you took a ride it would take you right through some sizable cliff bands. That is my two cents anyway.
There may be a way up through some of the cliff bands without traversing all the way across, but they would be quite steep I think. And you might start running into mixed terrain real quick, but that is just an assumption. The problem is that you could possibly spend a lot of time trying to find a good/safe way through them.
Thanks for the reply everyone. Someone who has done it contacted me and there is a hidden 55 degree couloir in the rock band below the face that leads right up to the climb.
Oh, that is awesome to know! If you get up there could you post a pic to the MP page as to its location? I was considering giving it a run this spring as well, and I like your idea much more than mine haha.