An old post of mine on using JFreq and Wordscores in R still gets frequent hits. For some documents, the current version of JFreq doesn’t work as well as the old one (which you can find here [I’m just hosting this, all credit to Will Lowe]). For even longer documents, we have a Python script by Thiago Marzagão archived here (I have never tried this). And then there is quanteda, the new R package that also does Wordscores.
Having said this, a recent working paper by Bastiaan Bruinsma, Kostas Gemenis heavily criticize Wordscores. While their work does not discredit Wordscores as such (merely the quick and easy approach Wordscores advertises — which depending on your view is the essence of Wordscores), I prefer to read it as a call to validating Wordscores before they are applied. After all, in some situations they seems to ‘work’ pretty well, as Laura Morales and I show in our recent paper in Party Politics.