Some econometric software packages have model search tools such as those proposed here.  During my working days I have seen tools such as these being misused.  I would be sure that no one on this list would use such a tool to search for a model that "fitted" the data well  and then present the final t-stats etc, as if they were the results of the estimation of some model derived from theory.  This is either dishonest or incompetent.  On several occasions when presented with such work I tried to explain the statistical problems to be told that if there were such problems the routines would not have been included in the software.  My recommendation would be not to include such a routine in gretl.  Gretl is an excellent econometric package and we should avoid introducing routines that bring econometrics into disrepute.