How do I switch discs in Popstarter?

https://imgur.com/t6sCDwT

Or when launching the game through OPL daily build?

So I've used discpooper.exe.

For example Alone in the Dark has this in the discs.txt file in the disc one and disc two folder

SLUS_012.01.Alone in the Dark (Disc 1).VCD
SLUS_013.77.Alone in the Dark (Disc 2).VCD

Where as in the VMCDIR.txt both files have something like this.
SLUS_012

What am I supposed to put in the...

How do I switch discs in Popstarter?