Create spatial_ref_sys entry from srtext ?

Hi list !

I received a bunch of shapefiles with a .prj file.
I can't find the projection in the spatial_ref_sys table (it looks
quite strange, it says "IGNBelg_Lam72").
How can I insert a record for this projection in the
spatial_ref_sys table ?

Here is the .prj file content :
PROJCS["IGNBelg_Lam72",
GEOGCS["Hayford 1924",
DATUM["<custom>",
SPHEROID["International_1924",6378388.0,297.0]
],
PRIMEM["Greenwich",0.0],
UNIT["Degree",0.0174532925199433]
],
PROJECTION["Lambert_Conformal_Conic"],
PARAMETER["False_Easting",150000.013],
PARAMETER["False_Northing",5400088.438],
PARAMETER["Central_Meridian",4.367486666667],
PARAMETER["Standard_Parallel_1",49.83333389],
PARAMETER["Standard_Parallel_2",51.16666729],
PARAMETER["Scale_Factor",1.0],
PARAMETER["Latitude_Of_Origin",90.0],
UNIT["Meter",1.0]
]

Thanks a lot !

Regards
--
Arnaud