In the Lavastorm (LAE) product the configuration for the temporary file directory (and log file directory) are stored in your 'site.prop' file.
For a standard install this file will be in the <installDir>\conf directory, e.g.
C:\Program Files\Lavastorm\LAE6.1\conf\site.prop
It may alternatively be located under your username, e.g.
C:\users\<user>\...\conf\site.prop
You will need to modify the values for the ls.logDir, ls.tempDir and ls.brain.brxDeploymentDir properties, assuming you want your log files located near your temporary data files.