You dont need to upload the xternal parameter file to PC to execute the load script. Place the parameter file in the LG machine if you are running with a single LG or place the file in a location where the LG's has access to the location and the file. Seek the help of your network administrator or your PC support desk team to perform this activity.
In Vugen Goto tools->Performance center connection->provide the link of the performance center (eg:http://testlab/loadtest), give username & pwd. Once Connected Goto File->Save it will ask to save the script by name->the second option it will ask is 1. Upload run time file 2. Upload all file choose 2nd option,this should help move all the data files as well.