Use the /!X and /!C parameters after the DTSRun command (/!X says do not run and /!C says copy results into clipboard). You will get the package name in clear text in your clipboard. Paste to notepad, and you will see it.
Detail is here:
1. Copy the DTSRun command line from the job step (including the very long encrypted string!)
2. Open a Windows Command Line Window and paste the command into it.
3. Add /!X and /!C to the end of the DTSRun command. (/!X says do not run and /!C says copy results into clipboard)
4. Execute the command. (You should see DTSRun: Loading … and DTSRun: Executing …. as is displayed below and the cleartext parameters should now be in your paste buffer)
5. Paste the cleartext parameter string into notepad.