How to convert filter Expression to Expression<Func<someType, bool>>?

[IT Department]

I have some operations that require me to perform updates on items (in bulk, possibly hundreds of thousands, so on the server end), but restricted to the items filtered by the user in the grid.  I'm aware of the Telerik.Windows.Data "Where" extension that returns an IQueryable given the grid's filter collection, and that IQueryable has an Expression property that seems to be just what I want.

The signature of my update statement is 

Update<TResult>(Expression<Func<TEntity, TResult>> entity, Expression<Func<TEntity, bool>> predicate);

You can disregard the "entity" argument, that describes the data to be updated.  How can I use Expression returned from the "Where" method populate the "predicate" argument?

Thanks!