Yeah it's not difficult. I do recommend a bit of anti-seize compound on
the threads, doesn't take much, just a little dab. It's steel threads in
an aluminum cylinder head so you have to be careful not to get it
crossthreaded or over-tighten it, you can strip the threads right out of
the head.
If you're not certain, you can pick up a cheap but usable torque wrench
for under $20, you're still saving money over having a shop do it. You
might borrow one from a friend or neighbor too.
