If you don't have any access to the repository machine, I think your easiest option would be the Data Dictionary + dummy rule option
Repository > Data Dictionary > Scripts. When you upload it, make sure the content / mime type is set to
Mimetype: Java Script, changing it in Edit Properties if needed
Now, create a dummy folder somewhere. On that folder, pick
Manage Rules, create a new rule. Set it to run on
Items are created or enter this folder and perform action of
Execute Script and pick your newly uploaded script as the one to run
Finally, create a random file in your folder every time you want to run the script!
Edit: If your script has any problems, then these will only be logged on the repo side, which you won't be able to see. Probably your best bet therefore is to wrap the whole thing in a giant try/catch block, and have it log the exceptions into another file, in a non rules folder!