Sillage is a French word. Unlike many French words, it doesn't sound pompous or pedantic to pronounce it correctly whilst speaking english: Using that as a springboard, you would say:
So, "sea," like the marvelous sea, and "ah" like open you mouth and say "ah," then the hardest if you don't speak french at all--the "je." If you remember that Book by Boris Patornak, which later became an epic movie in the 60's with Julie Christie & Omar Shariff, "Docter Zhivahgo" --the "age" in "sillage" sounds exactly like AH-ZH. SO: SEA-AHZH. there is no "L" sound at all, as, in French, two ll's together become pronounced most often like "ee"
From the French point of view, in perfumery, when one speaks of sillage, it means eqaully how you yourself experience the scent on your body--the little puffs of it you'll get, or the comforting shroud that follows you all day: Here is where you find if a scent id really "you," because if the sillage isn't right, you feel like you're wearing someone else's shirt, or you are in disguise. Sillage is important. It is not "Projection." It is a kind of relationship that you and your peers have with the particles of air that float about you: How they dance. Ultimately, Sillage is everything. It is the true soul of any scent: a scent with no sillage is like "une journee sans pain"