how can I rip sprites from project64?

Well rip the usual way, take a screenshot of what you want and remove what you don’t need! Or you can use Animget. If you want a tutorial to learn how to use it go here.
If you don’t want to use Animget, here is another good tutorial : Click Here.

Note :Those tutorials are for 2D games, so I don’t know if they will work well with pj64.