Diacritics and Composites: Need help encoding glyphs as accents

[Panafrofontdesigner]

How can I get certain glyphs to act as accents? I want them to type/print above or below the letter, but so far they just sit on the side as another letter...

[Alex Petrov]

May be give them zero width?

[Der FontMeister]

You may want to offset the character to the left of the em square so that the accent appears ABOVE the previous character. When Alex says zero width you must be sure NOT to place the right-sidebearing on TOP of the  left-sidebearing.

Zero-width does not really mean no width -it must have one em unit of width...

Jimmy G.

[jmaul]

Since glyphs as such are considered "floating", why not just let the user move them where they want?
Type Tool's default glyphs helps give us direction on the common combinations with vowels and such.