Just tell him what you'd like him to do. For example, if he kisses you "too passionately" tell him you'd like him to be more tender and move slower with less tongue and less saliva. It's not that you can teach one how to kiss... You can just tell him what you like. Or easier solution, find a movie scene that you like of two people kissing and show him: "This is how I'd like you to kiss me". Easy as that. And if these don't work, well I'm out of ideas. Good luck.
Did you ever think it mite be you/the girl that needs to learn how to kiss.kissing for dummies the big yellow book.