Firstly, to carry out any actions that modify XSplit Broadcaster, then XSplit Broadcaster must be running with the exception of Custom URI which will launch XSplit Broadcaster when executed.
Right now, it’s not possible to change the recording folder using XJS, however I think this is something we could explore adding.
As for changing the settings of the Akamai plugin, it’s currently not possible to modify any output plugin using XJS. However, if I could understand your use case a little more it may help. In the meantime, you may want to check out our Custom URI Scheme that allows you to add things like outputs with custom settings.