Goal Seek alternative in Excel Services

Hi,

I have a need to use "Goal Seek" in my excel.

The problem is that I am using excel services and I need the system to automatically execute the Goal Seek and return me a value. I am calling Excel Services from my ASP page on SharePoint to retrieve an excel file from my document library and load it in Excel Services.

Since Goal Seek is not supported in Excel Services, I need to know of any alternative available in UDF or excel formula.

Thank you.
Samer