OK, I'll rephrase. How is that different than using the PFL button?
I have been using CL5 consoles for 10 years and I have never had an issue listening to a single channel via the PFL.
Mac
To be ridiculously pedantic, it's a "Cue" button.

The PFL/AFL modes are selectable for Inputs and/or outputs.
to the OP: If you're looking for "Solo In Place" which sends whatever you have Cued and ONLY that thing to the stereo bus, that is located in the Monitor section/Cue subsection. Hitting the "On" button next to Solo on the lower left engages SIP. There will be a lot of blinking and warning going on while you're in this mode so you don't forget and put your headphones on mid-show and cue something up thereby giving your audience a "bass solo" of whatever, not that i've ever had that happen.