Yeah it's a little different
You won't be able to drop your 10" blade down far enough to start it at a 45 degree angle ...so use a circ saw blade like 7 1/4 or a dado blade say 8", and then raise it up for the new angle.
Or you can route out the slot to a thinner section right over the blade and use your 10" blade. Just don't go all the way through!
The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)