You can add low frequency responses in both transmit audio as well as receive audio in SSB mode.
Basically you shift the carrier point in relation to the audio passband.
You can change these values this way:
Push the function key until the menu appears. Now go to the following menu:
(note that default all four values are set to 0 Hz)
CAR LSB R (menu 15). Here you can adjust the LSB reception carrier and effectively at +300 Hz pull down the audio band pass down to 100 Hz.
Same story for CAR LSB T (menu 16) - this is for the transmit part.
Again same story for menu 17 and 18, for receiving and transmittin gon USB. Note that for the USB part, you'll have to shift the other way -- e.g. if LSB is at +250, the USB should be at -250.