Lycanthrope template for NPCs and Challenge

[Mr Adventurer]

So I'd like to have an antagonist NPC who has class levels and is a lycanthrope. I've got the rules for each of these things individually, except I haven't found how to calculate the Challenge of a creature after I apply the lycanthrope template to it. Have I missed it somewhere? Alternatively, I spotted a guide to making your own creatures and assigning Challenge to them - will have to stat up my guy, then go through that system to assign him a Challenge?

[Giant2005]

will have to stat up my guy, then go through that system to assign him a Challenge?

Sure will.
Or you can just wing it - the creature's CR doesn't really matter, just give the party a creature as challenging as you want to be and give them as much xp as you want them to have. Winging it is a formula that has worked well for dozens of systems, for dozens of years.