You mean this?:
High resolution texture downloads for Mercury, for use in Orbiter Space Flight Simulator. Based on images from the MDIS instrument aboard NASA's Messenger probe. See the installation instructions for general installation help. Additionally, since the original installation of Orbiter2016 used an old texture format for Mercury, you should also replace your <orbiterroot>\Config\Mercury.cfg with this version. And if you install Label.tree surface feature labels (Orbiter beta only!), you need to copy Label.cfg to <orbiterroot>\Config\Mercury\Label.cfg