Has anyone been successful in negotiating WLS Approval when being hired.

In june of this year I was laid off from my company. My employers felt that the work experience that I brought to my postion was impressives and have sought me out to offer me a new postion. My insurance company with them is Premera Blue Cross PPP with a written exclusion. Before being laid off my intake appointent with the Wishcenter recieved approval and was paid for however after I discontinued my duties (but still was eleligle for company benifits) I was deined the surgery. As I am anticpating accepting the new position I will ask them to pre approve my sugery as a condition of my employment. I would like to know if any of you have any thoughts, suggestions or experience in negotiating WLS approval with your company.