Using Arcpy, how to add selected features to FC AND attributes?

This should be pretty simple, but I'm not finding a good answer in Help or Google. I have a section of features from a feature class. I want to essentially create one feature from them and add them to another existing feature class along with one or two attributes. I'm attempting to create a tool in ArcMap 10.0 that allows my users to select the features, open the tool, add the information about the soon-to-be-created feature into the text boxes in the tool and when they click OK, have it create a new feature out of the selected geometry (polygon) in my other FC with attributes filled out from the user's specifications. It looks like arcpy.CopyFeatures_management() will create a new feature in a NEW feature class, but how do I tell it what attributes to use and to add to an EXISTING feature class?

Thanks for any direction.