How do you write 縮めて in IPA (International Phonetic Alphabet)?
It's pronounced [[c̟ɕiʑimete]], although in careful speech it would probably be [[c̟ɕiɟʑimete]]―there's no contrast between [[ʑi]] and [[ɟʑi]] in Modern Japanese, so the word will be understood either way.
For the pronunciation of ち and ぢ, see section 4.3 "Affricates" in Vance's The Sounds of Japanese (2008), starting on page 82. Most of this section is available online at Google Books.
Writing IPA for Japanese is really quite simple in most cases.
Look up IPA for Japanese and use the sounds there to write your word.
ꜜ is a tone drop, although here on Japanese.SE we have a fantastic way of writing pitch for かな: ちぢめて【LHHH】. (Correct pitch due to @非回答者.)