Humm...
IIRC @Apache Thunder stated that the arm7's SCFG is always locked unless you boot a cart, so I don't think so, without and bootrom exploit RocketLauncher is the only way to have full control over the system.
Even when booting a cart, SCFG is locked. The only thing that has unlocked SCFG is Launcher, hence RocketLauncher exploiting the launcher. Before booting a game (cart or otherwise), Launcher locks SCFG.
Yeah you have to exploit Launcher or the stage2 bootloader on NAND (equivalent to FIRM partitions of 3DS....sorta). No official software besides Launcher runs with unlocked SCFG. Not even a few of the system Dev apps had it. twlNmenu has a few other things unlocked (a dev app that has both slot-1 and nand enabled), but even that app doesn't have unlocked SCFG. That app only is signed for dev hardware anyways so you can't use that one on retail hardware.