Device Tree (overlay) entries for LDOs & nRESET for CODEC?

I have two LDOs enabled/disabled by the same GPIO. One provides 3.3 V to the AVDD and DRVDD pins of the audio CODEC, the other provides 1.8 V to the DVDD pin. The remaining IOVDD pin is supplied by the 3.3V pin on expansion header P9.

Looking at BB-BONE-AUDI-02-00A0.dts, all four supplies reference ldo4_reg. I need to create a regulator node in my overlay for my own regulators, but I'm not sure how to indicate they're controlled by a GPIO. These regulators are not controllable via i2c or anything like that, they're just on or off. They can be off in suspend modes or of audio is off. Note that they have to be on for the CODEC to respond to commands.

Can I just put a regulator node in my overlay? How do I know what @X number to use (must it be greater than all the other defined regulators)?

I also need to control the CODEC's nRESET from a GPIO. Looks like the binding supports "gpio-reset", the gpio pin number (would that be 51 for gpio1[19]?). Do I need to also set it up in the pinmux node (as an output, etc)?