Chuck,
See if I can add a little, to what Lew as said.
With respect to Lew, forget the manufactures data regards feeds and speeds they are not for you and me with home workshop type mills. Semi and industrial machines fine.
Make sure the work piece is held in a rigid manner.
Only cut one side of the dove tail at a time.
Use the largest cutter possible.
Only cut in conventional milling. (Not climb milling)

Make sure the two unused axis are locked.
Take it slow and steady.
First cut the slot out with a normal end/slot mill.
Now for the dove tail.
Start with a spindle speed 500/700 rmp first cut tiny .005, a slow and steady speed careful when the cut first starts making sure it is just cutting not too fast listen and feel the machine. At the end of the cut, remove all chips then return the cutter to the start. Two ways here either leave it running, or stop the spindle and return, if you stop the spindle you can then turn the cutter by hand so it does not touch the work piece.
It is not a good idea to cut on the way back.

Now remember each time the cutter it set into the work piece the load on the cutter increases, there is more cutter surface in contact with the work piece. So as you cut more of the dove tail you may have to reduce your feed. Try to keep clearing the chips away.
If you are happy and the machine was happy you could in crease the speed, and feed rate, keeping the same .005 cut. Everything good no bad vibrations increase the cut say to .010 or even .025. Listen and feel the machine, it will start to complain, take notice or your cutter may break.
Finish cuts of .002 or even .001 if you have to are OK, just increase the feed a little.
Chuck, it is a bit of a slow process, take your time, feed especially slow when the cutter just starts to cut, then speed up.
Try to keep the chips away.
I hope this helps a little, its one of these things that is much easier to show than explain.

DaveH