Why don't just add this line as option?
data_location_override = se_white_list

According to https://twiki.cern.ch/twiki/bin/view/CMSPublic/WorkBookXrootdService
you don't need to add any script. If the dataset is published (as supposed by you using DAS), then you can ask to CRAB to figure out where the data are. 
I've never used that option but I can try tomorrow.