You will add your routine in atlas-lp.base with an additional @ROUT keyline, but also do not forget to update the include file atlas_lapack.h at the bottom of the file as well. You will need to add your routine to the prototype part, as well as to the macro renaming part. Examine the basefile for details.
Once it is extracting, use your LAPACK-debugged tester to debug your code.