Yes, just use analogWriteResolution() and analogWrite(), the same way you would do for PWM. By giving those functions the DAC's pin number, A12 or 26, they'll control the actual analog output from the DAC.
The audio library currently doesn't work on Teensy LC, because it requires the more powerful DMA controller and DSP extensions of Cortex-M4.
The Talkie library is an example of one that does work on Teensy LC and uses the DAC output. As I recall, it just uses analogWrite.
If you *really* want to dig into the actual code to directly access the DAC, the just look at
the analogWrite code. The part specific to Teensy LC's DAC begin on line 531. As you can see, once the DAC is configured, you can update it by just writing 16 bits to the DAC0_DAT0L register.
For complete documentation about the DAC's details, you'll need the
reference manual. The DAC is covered in chapter 30, starting on page 557.