I have a set of X, Y, Z coordinates in the Earth Centered Earth Fixed (ECEF) geocentric system. I need to convert them from ECEF coordinates into Latitude/Longitude coordinates using an inverse Icosahedral Snyder Equal Area (ISEA) projection. I see that this projection is available as part of the PROJ.4 library (http://proj4.org/projections/isea.html). However, I am not fully sure how to use this to transform coordinates between the two systems.
Any guidance on how to use the ISEA projection (both forward and inverse) with PROJ.4 will greatly help, along with any sample code.