Hmm, never thought to try PlayOnLinux for running Windows DOSBox. Instead I use the Linux DOSBox.
There are some DOS games on GOG that have Windows DOSBox bundled with it, but you can still install the game with PlayOnLinux, then copy the game folder to your dosgames directory where it hosts all of your Linux DOSBox games. That normally works as well.
The installation is not possible automatically, the file (example: PlayOnLinux-wine-4.0-dos_support-linux-x86.tar.gz ) has to be downloaded then unzipped into the right place : ./PlayOnLinux/wine/... into a new folder that you have to create (example: 4.0-dos_support )
Then the user must change the version of the installation script in POL/POM from the Settings window.