Sadly, it's pretty well dead as far as I can tell. The Write software is very outdated, lacks features and is buggy. It is possible to create your own stories and upload them to the Choosatron using it, but it is not a very straightforward process.
Have a search around these forums, there are a few posts that explain how to do it.
But overall this project has ended up a big disappointment. I've tried tweeting the creator once or twice (his Twitter is @j3rrytron), asking if there are plans to finish development, but have had no response.
Real shame, as the device had so much potential if it had decent software support. My kids were initially really enthusiastic for it, but their interest waned as it was too complicated to work with.
If you can't find the relevant threads to get at least some basic functionality, reply here and I will see if I can help.