You have to put the selector on "A", read the meter reading and then change the shutter speed to the manual setting desired. The desired setting can either match what the shutter speed the meter indicated or you can compensate based on the scene. You are always selecting the aperture manually.
The is a very complicated way to meter in manual mode. My SRT-101 looked similar to the XG9, but had no Automatic mode and you had the meter available all the time.
In your case you will have to keep switching back to the Automatic mode to grab a reading of the shutter speed.
It will be very helpful if you memorize the f-stop and shutter speed scales so when you go to set a shutter speed and then realize you wanted a different f-stop you don't have to go back to the A setting and set the new f-stop and then find the new shutter speed, you can just do the mental calculation to come up with the new shutter speed based on how many stops you changed your f-stop.