If you have the private key, you can edit the script and save changes. If you have the public key, you can run it?
No, that's not really going to work.
The most common uses of tokenisation for are:
1) To protect commercially sensitive code.
2) To hide passwords or similar data.
Now, to be able to "access" the code to execute it you have to be able to revert it to a form that the interpreter understands, in other words it is de-tokenised to a parsed form in memory.
If you have access to the source code all you need to do is add a very simple routine to dump memory to a file once the tokenised code has been parsed. The "de-tokenised" version of code is likely to be ugly but servicable, and of course all strings (such as passwords) are trivial to expose.
