You don't say in what context you are aging your glossy paper? ,so I refer my comments to aging photographs , depending on what effect you want you can add effects whilst printing in any Photoshop type program , you can also make up scratches , blemishes, colour bleeds etc etc , just run the paper through the printer a time or two adding very small effects and build up the overall effect., the very process of printing will add creases and the aged look can be built up over time. sand-papering the edges lightly can also add an agesd effect as can rubbing charcoal or pastel colour into the paper .