Custom a new coordinate system in Bentley Map V8i

I did not understand if the seed.dty file is to be copied in the same directory of the program or may be or can be copied in other directories (for example C:\Bentley_Project). In addision in my configuration variable is not present the MS_GEOCOODINATE_USERLIBRARIES VARIABLE and so I have create it. Neverthless, when start Bentley Map and open Select Coordinate system is not present custom library. What is the detailed procedure to resolve this point?