Mixer to CB

[eroche]

I'm very new to CB radio.
Is there a way to output sound from a Mixer (Second Photo) and feed it into the microphone port of a CB transmitter (RCI29-80, First Photo)? The microphone has a 4 pin socket - it looks like Midland type.
I use the RCI29-80 transmitter for transmitting only, not receiving, so that, effectively, when it is operating it is always switched to the "transmit" mode of operating.