link_to_remote - pass javascript variables

<%= link_to_remote "sometext",         :url => { :action => :someaction, :x => "object.getX()", :y => "object.getY()" },     :complete => "onComplete(request)" %>

problem: object.getX() passes unevaluated. how to pass value of object.getX() and bind it to params[:x]?