I've written my own text format for SCPI in *.txt. How do I use these for SCPI completion within VEE 9.0. What tool should I use?

You can use the tool found within Keysight.com. Just search using the keyword "Keysight VEE SCPI Tool". This tool will help you convert your SCPI command residing in *.txt file to *.xml. To use this SCPI command file in VEE SCPI Completion, you need to save it in "~installdir\ScpiXmlFiles" folder. For example, C:\Program Files\Keysight\VEE Pro 9.0\SCPIXmlFiles.