Uralic phonetic alphabet or UPA – unusual diacritics

I am writing a linguistics MA thesis in LaTeX, and I will possibly need to use the Uralic Phonetic Alphabet, for example in glossing environments. What would be the best way to do this? I've seen there are separate packages to facilitate using IPA, but my department generally prefers UPA. Mostly I would need letters like a̮, š and ĺ. The source text is in UTF-8 Finnish.

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In XeTeX or LuaTeX, you could use a font which supports these rare characters. If I'm not mistaken, examples of such fonts include newer versions of Times New Roman (very much beloved at universities) and Charis SIL. If you went with this solution, you wouldn't need any packages specifically for UPA. –  jemp Sep 29 '11 at 11:25

If I input

\documentclass{article}

\usepackage{fontspec}
\setmainfont[Ligatures=TeX]{TeX Gyre Pagella}