Trim Dressing is basically Tire dressing (Wet Look) without the water. Waterbase formula.
Directions: I suggest you use this the evening before you wash the car just to give it overnight to soak in all the trim then when you wash the car the next morning your just washing off the residue that didn't soak in. Simply wet a rag, any rag then wring it out. pour a little dressing on rag and wipe all plastic molding thourally. Some would like to use this tires but thats a personal choice.
Detailers tip: always wet a rag/towel then wring out prior to adding chemical to it. You will use less chemical.