As I learnt yesterday on IRC, there is syntax modify-services to be used in system configuration. Unfortunatelly not all the services which configuration could be changed has exported bindings to do that.
This patchset should address that. Also note, that `screen-locker' and `static-networking' have inconsistent naming scheme compared to others. I'd go with `screen-locker-configuration' and `static-networking-configuration' but my Scheme-fu is weak.
