We don't have any scripts to handle that. For the most part I've tried very hard to avoid the need to do so since .cho files aren't particularly nice to work with, but ACBC has some things that don't translate fully into the .csv formats.
The best advice I can give is to just meticulously follow the documentation as to their structure (see https://www.sawtoothsoftware.com/download/ssiweb/CBCHB_Manual.pdf
You'll need a script that reads the file line by line, and if you parse and interpret it correctly, you should be able to avoid any guesswork as to what you're reading. For example Line 1 will tell you how many questions that respondent will have, and Line 2 will be the first question and tell you how many response options to expect in the next coming lines. As soon as the lines for one thing are finished, you can safely read for the next thing.
General script for parsing an R file line by line.
For splitting a line into pieces and converting it to a vector: https://stat.ethz.ch/R-manual/R-devel/library/base/html/strsplit.html
Between those two things, you should be able to get things into a readable R format. Hopefully that leads in a helpful direction.