Patricia Lafayllve has some ideas on "apartment wights" in her Practical Heathen's Guide, so why not office wights? All you need is a candle and a bowl for offerings. She suggests a simple invocation of the "wights of this place". Another idea of hers is to build a wight-home. Find a stone about the size of a grapefruit and ask the wights if they want to move in with you and leave an offering in place of the stone. The stone is then placed on a shelf with the offering bowl and candle.