converting multiple .csv files to one multi-sheet .xls spreadsheet - unoconv?

Is there a way, ideally using the command line, to convert multiple .csv files to one multi-sheet .xls spreadsheet?

I tried unoconv, but it doesn’t seem to work with this version (5.1.0) of LibreOffice.

If there’s an API that works in awk, or pascal, ideally, or anything else, that’d be good to know too. I’m using OS/X 10.11.3, but a solution using linux would be great too.

If it isn’t possible using LibreOffice, I’d be most grateful for any suggestions for alternative ways to do this.