I got accepted in to Sauder last year, but ultimately didn't accept it because I was refused housing.
My average was around 90%.
As for the requirements, you're going to need Math 12 no questions asked. English 12 is needed, along with the LPI.
As for the other courses to take, they recommend taking 1-2 Science 12 classes.
It might sound lame, but Calculus 12 is also a very important class. You can make due without it, but I'm taking an Economics based Calc class this term, and if it wasn't for my previous knowledge in the class I would be tanking.
As for the supplemental stuff, I just played on sports teams from grade 8 - 12. I played some instruments and worked at a few different jobs. I also did some volunteer work at some ski swaps.
The supplemental application is really really important. Choose your references carefully.
I'll probably be transferring there next year if my housing gets approved this time around, since I need some of the specific second and third year classes they offer.
Good luck!