I find this interesting too. Periklis, if you've successfully used libsvm for econometric purposes, please give us a (at least) a brief description. Libsvm looks like something we could work with quite easily.
The profile of machine learning has been raised recently by the article by Mullainathan and Spiess in the Spring 2017 issue of the Journal of Economic Perspectives, and it's possible this is something we'd want to explore in gretl.
Allin Cottrell