You can find the latest version here . I'll include all the commands I ran below to get this up and running with the current latest version of Tex Text and Inkscape 0.91 r13725
wget http://pav.iki.fi/software/textext/textext-0.4.4.tar.gz
tar -xvzf textext-0.4.4.tar.gz
cp textext.inx textext.py .config/inkscape/extensions/
Restart inkscape (if required).
Within Inkscape and you can find the new extension under Extensions > Tex Text.
Type in some LaTeX text and it will insert the rendered text into your document.