Using OSD for ROV, custom parameters

Hey guys, for the people who know a good deal about FPV with OSD boards, I need your help. My underwater ROV project needs the capability of displaying parameters over a video feed from the ROV. I discovered what OSD boards can do, and that is exactly what I need except I need to create my own parameters such as depth, cabin pressure, water pressure, and range just to name a few. So I need to figure out a way to get rid of the avionics parameters that are programmed in the board and replace those with my custom parameters. Can someone help me out?