As an FYI for any transliteration I do, specifically for aliens, I tend to use the following (Parenthesis indicates unicode entity numbers, capital and lower case) ampersand notation for it:
š indicates a sh sound (U+0160 U+0161) Š š ž indicates the sound of s as in measure or pleasure. The same as the Russian or Ukrainian ж. (U+017D U+017E) Ž ž č indicates a ch shound as in cheese. (U+010D U+010C) &#268; č; ð indicates a th as in that (U+00D0 U+00F0) Ð ð; þ indicates a th as in thin (U+00DE U+00FE) Þ þ;
Most windows fonts include these five symbols. I tend not to even think about the use of these; they're easy access on a mac using the extended keyboard.