The rendering of Pali in the Roman alphabet is already
phonetic. You just need to know the rules. http://www.accesstoinsight.org/lib/auth ... #pronounce
Assuming, of course, that it is written with the diacriticals (or some code for them) so you know which vowels are short and which are long, and when there is a "ng" sound (ṃ & ṅ) and other stuff like ñ.
English speakers mangle Pali (like they mangle the native language in my country, Maori) because they think that just because it uses Roman letters the pronunciation should have something to do with English - which is a curious attitude... So they can't accept, for example, tha "e" is pronounced as "aye" (and always gets emphasis). [Happens to be the same pronunciation as Maori, which is not surprising since that's also a phonetic rendering...]
The other big challenge is the syllables. After a while you'll realise that certain letters never end a syllable, so you won't have a problem. The double consonants should be pronounced. the "h" in "kh" indicates an aspirated sound, etc...
"v" usually comes out as "w" because languges like Thai don't have a "v"...
Note that Upekkha splits up as U-pek-kha (U-payk
and Dukkha as Duk-kha
Doing some Pali chanting while following the text helps a lot: http://www.forestmeditation.com/audio/audio.html