You can inject a brisket without a problem. In beef, unless you use an exceptionally dark marinade, it won't even leave tracks.
I have injected beef brisket using 1 portion apple-cider vinegar, 2 portions canola oil, 1 portion water, 1/2 portion wine. You can add seasonings to taste: onion powder, garlic powder, herbs, salt, and pepper.
Put the whole mixture in a blender and blend until everything is very fine. You don't want to clog the injection needle. I do keep a straightened paper clip handy to unclog the needle if that happens.
You can inject just about any time before cooking, apply your favorite rub, and you should get moist, delicious brisket.