This is what I am using to run on multiple concurrent VM's on saucelabs. I have a 1-click batch file that uses start pybot to invoke parallel execution. Example:
ECHO starting parallel run on saucelabs.com
cd c:\base\dir\script
ECHO Win7/Chrome40:
start pybot -v REMOTE_URL:http://user:[email protected]:80/wd/hub -T -d results/Win7Chrome40 -v DESIRED_CAPABILITIES:"name:Win7 + Chrome40, platform:Windows 7, browserName:chrome, version:40" tests/test.robot
ECHO Win8/IE11
start pybot -v REMOTE_URL:http://user:[email protected]:80/wd/hub -T -d results/Win8IE11 -v DESIRED_CAPABILITIES:"name:Win8 + IE11, platform:Windows 8.1, browserName:internet explorer, version:11" tests/test.robot
-T tells pybot to not overwrite result logs but create a timestamped log for each run
-d specifies where the results will go
Works like a charm!