I have released a version of the ESP8266 firmware based on the esp_iot_sdk_v1.1.0_15_05_26 sdk. This firmware adds new Wi-Fi functions that don't write the configuration to flash once changed (more on this later).
These functions are an addition to the AT command set which uses the wifi_softap_set_config_current function that was added in the 1.0.0 SDK:
AT+CWSAPID: Set parameters of AP with exiting password and encryption. AT+CWSAPID=<ssid>,<channel> AT+CWSAPCH: Change AP channel. AT+CWSAPCH=<channel> AT+CWSAPRI: Re-initialises AP. AT+CWSAPRIThe firmware source and binaries are available here.
By default, the Makefile is set to build for 512kB flash modules (no "cloud" updating possible). So this should work fine on all ESP modules. This SDK also includes the AT+CWMODE_CUR and AT+CWSAP_CUR AT functions to change further AP modes.
Write eagle.flash.bin to 0x00000 and eagle.irom0text.bin to 0x40000 (if using the nodemcu programmer, program eagle.irom0text.bin first).
Baudrate = 115200
AT Commands have to be capitalized, and end with "/r/n"