These use cases are just to get your mouth watering, there is virtually nothing you cannot do with this. You may ask, can I write to a database or JMS or File system? Well, are there Java API's to do that?
The download and config are quite simple, just download the MftJS.zip file and unzip it into your MFT <DOMAIN_HOME> folder. Then open up the README file in mft/js/README and follow the instructions. There is actually a library of samples you can use all driven by an Action parameter in the MFT RunJS callout UI shown below.
The Location and Function values are defaulted but you can override them and adjust the ScriptParameters as you like. There is even a special obfuscated Password you can use for hiding parameters. There are end to end transfers provided you can import, deploy and run to get you started as shown below.
Geeze, what will they think of next ;)