The WRKSPLF panel is an IBM supplied panel, as far as I am aware there isn’t a way to add an option to this. You could always write your own version of the WRKSPLF command – but that’s likely to be a lot of work.
If you use certain GUI interfaces (JWalk for example), you may be able to add what looks like an option but actually runs a command or script to achieve the same thing.
You cannot add an option 0 but, in V6R1, you can add options A-Z on WRKSPLF, WRKOUTQ, and even the System/36 environment D P command. This is covered in my ‘What’s New in System APIs for V6R1′ presentation along with an example of adding option ‘P’ for Print Next. You could easily also use ‘A’ for archive, ‘F’ for fax, etc. This presentation is not currently on my web site but if you would like a copy just contact me directly.