Metadata configuration for a custom button

Hello Experts,

I have a requirement to add a new Custom Button in SC header. This button is NOT required when a requester or user Display or Edit this SC.

Button is required only when an Approver of a particular level gets the Workitem to approve it, Selects the SC and clicks on Display.

I am able to create a new button using document at below path

http://scn.sap.com/docs/DOC-25271#comment-539479

As per this link, in Metadata we are using Set-Type 05. If I use 05, then button is available only in general Display and Edit, but not for approver.

Can someone please suggest if I need to use some other Set-type.

Thanks in advance.

Shyam Agrawal