Yup, get some good solid wood screws, with a flat head.

I would put the sub in, set it how you want (angled right), take a drill with a small bore drill and make some pilot holes so you don't split the wood.

Remove sub and use vacuum to suck out the saw dust from drilling (we want a presentable box right?)

Put sub back, line up holes, and screw it in place.

Keep in mind, you want to be careful with the screw driver, if you slip off you can push the screw-driver throught the cone or excursion and ruin the woofer. Been there, broke that, felt stupid.

Just go slow, take your time, appreciate it once its all put together properly.