Hardware AMux Component supports Analog Pins as input at the multiplexer input channels.
The Select lines can be Digital Input Pins. Since your design in this case requires 2 select lines to choose between the 4 pairs of the input Analog Channels, you can use Digital Input Pin.
In the Configuration Box, you can choose the 'Number of Pins' to 2. And also Select the mapping to 'Display as Bus'.
Now, when you connect the select lines to the pin, the wire appears to be thicker (which is an indication that it is a Bus, not a single wire).
In .cydwr, the pins can be chosen according to your convenience.
Let us know if this helps.