Parameters optimized using PARAM can be migrated for use in MOPAC. The simplest mechanism is to put the optimized parameters into a text file, para.txt, for example. Then, using the EXTERNAL option with MOPAC, read in the values in that file. This would allow the full range of functionality of MOPAC to be used with the new method.
Eventually, there will be a need to make a permanent change to MOPAC, to allow the new method to be fully integrated into the program. This can be facilitated by use of an otherwise undocumented keyword, DEP. When a MOPAC job is run using DEP together with EXTERNAL=<text>, a unique file called parameters_for_PM6_C.F90 will be created. This file can then be re-named and edited as necessary in order to show that it refers to the new method.
Obviously the MOPAC job to create this file does not need to be complicated. For example, the following file would be adequate for this task:
DEP EXTERNAL=para.txt Create a FORTRAN-90 file containing parameters for the new method H 0.00000000 0 0.0000000 0 0.0000000 0 0 0 0