How do you cut slots for trade points?

[BowEd]

Personally dieselcheese I make all my arrows self nocks.Might be good practice when trying to cut a slot for a trade point.Cutting slots for nocks are little at a time process most times checking like said to be sure the cut is straight and centered.I use 2 hacksaw blades taped together to get close then have little hobby files to finish.I have 1 small round file that is exactly the circumference of my serving on the string.I made a short section of serving that I use to test with while making the nocks.My nocks snap on lightly to the string just as plastic ones do.They come off with the tap of my finger but hang on enough onto the string by themselves too.
Putting horn inserts 1" long opposite your nock can help preserve the integrity of your nock too.Don't think that's needed for your trade point mounting though as good wrapping below trade point will prevent splitting.
I wrap all self nocks and trade point mounts a good 1/2" to 3/4" below slot.I use diamond nylon serving put on very tight and then sized with very thin super glue.Not all that primitive or paleo but I've never had one split even after being robin hooded a couple times.

[Buck67]

I cut the initial slot on my bandsaw.  Then I fold a piece of 100 grit sandpaper over 4 times.  Start working the sandpaper down into the slot.  When the sand paper works easily the slot is the right size for a trade point.

[Marc St Louis]

I cut the slot with the bandsaw then flip it over and go through the same cut from the other side to even it up. Like Clint I also dress up the cut but I use sandpaper folded and refold if I need to get wider. I also like to start with a pre-tapered end. This helps me keep centered.

I do like Pat but use a guide that I made which has a stop, I use it for points or selfnocks.  The guide is nothing more than a piece of wood with a slot cut into it for the bandsaw blade and a groove down the middle for the shaft to sit in and is adjustable for depth of cut

[Will Tell]

I use a Dremel. Slicker than Pelican snot. Takes less than a minute once you get on to it.

[BowEd]

Here's a pic arron of a jig I made that cuts perfect slots every time.

[JEB]

I have a commercial product that looks much like the photo that BowEd posted called a Nifty Nocker. Has a short slot for the nock end of the arrow and a long slot for the point end. The Nifty Nocker is made out of aluminum and works very well.