System for Trills

Hi,
can you tell me please, how I can make a special (small) system for my Trills. The problem is, that I can only wright notes which are next to each other (like a mordent). But I need to play a special order of notes for my trill (instead of "c-d-c" i want to have "c-e-f-e-c") I hope you understood, what i mean (-: