Since you have the cloth type I would avoid the Simple Green/409 level cleansers. Treat it more like a stubborn carpet stain. A raid of the S/O's domestic cleaning supplies might be in order. Start with the basics of a carpet shampoo (I seem to remember auto upholstery specific hand held models that were disposable and cheap but I forget where.) If the carpet shampoo does not do it, try either the steam cleaner, or some carpet spot stain remover. I can't recall brands offhand, just rummage around under the sink/linen closet or go to the household cleaner section of any Walmart or grocery store. If all of those don't touch it post back and we can take it from there.

Best of Luck...Lee