Custom Projection from an Arc PRJ file

Is there a way to create a custom coordinate system from an Arc PRJ file? A major city in this area uses their own coordinate system for their GIS and surveying. I wanted to bring some NED data into InRoads, but since the project is not in state plane coordinates, I am stuck.

I opened the PRJ file and while is it ASCII, but there is no explanation of exactly what is what.

And it is all on a single line, so the grouping of the data, which nests multiple times is not easy to follow.

Here is the data 0 I added a space after every comma so it would wrap:

PROJCS["815586_RSO_feet_rotation", GEOGCS["GCS_North_American_1983", DATUM["D_North_American_1983", SPHEROID["GRS_1980", 6378137.0, 298.257222101]], PRIMEM["Greenwich", 0.0], UNIT["Degree", 0.0174532925199433]], PROJECTION["Rectified_Skew_Orthomorphic_Center"], PARAMETER["False_Easting", 349.37],PARAMETER["False_Northing", 2588.1], PARAMETER["Scale_Factor", 1.0], PARAMETER["Azimuth", 0.0], PARAMETER["Longitude_Of_Center", -76.614429], PARAMETER["Latitude_Of_Center", 39.304635], PARAMETER["XY_Plane_Rotation",0.001], UNIT["Foot_US", 0.3048006096012192]]