I successfully exported an excel workbook from the workspace I was interested in thanks to your advice. I used :

P:\SOFTRAK\GVWIN\GVWin.exe /c /d"P:\DATA" /eDAT /uUSER /pPWD /t<yyyymmdd> /xds /xdd /xdw"path\to\my\workspace.gvs"

I got some questions I didn't find answer in the help :
1) Is-it possible to not open excel (even in the background) and just get the data as a .csv file instead ? I was not lucky changing the extension /e parameter
2) Is the saving directory /d linked to the user /u rights ? Because in my trials, I wasn't able to change the saving location
3) I really like the log file that's been created in the same time. Is-it only compatible when using the /xdw command ?

Have a great day,
Thanks again,

Alex