A lathe is kind of overkill, but it will work. Check Harold Hall's wonderful machinist pages for some tips. There is a plan for a simple end sharpener. You will need to set two compound angles, the primary relief and the dish to the center. He has a clever way of setting the primary relief just by using the height of approach towards a 6" grinder wheel. The indexing is done with a square index block. You will need one for each size of end mill unless you have a collet block.