No you cannot execute an S-Control from a workflow.
In fact, you can "call" it with outbond messages using a URL like : https://na3.salesforce.com/servlet/servlet.Integration?lid=<S-Control id>
But, an S-Control only works using client-side execution (ie HTML/Javascript). An outbond message calls an URL and that's it. In order for an S-Control to be executed, the web page needs to be open (as it is client side execution). With outbond messages, the url is only called server-side, the web page containing the S-Control is not opened at the client side.
In fact, you can "call" it with outbond messages using a URL like : https://na3.salesforce.com/servlet/servlet.Integration?lid=<S-Control id>
But, an S-Control only works using client-side execution (ie HTML/Javascript).
An outbond message calls an URL and that's it. In order for an S-Control to be executed, the web page needs to be open (as it is client side execution). With outbond messages, the url is only called server-side, the web page containing the S-Control is not opened at the client side.
This really help us.