Here's a quick little guide on setting up any of Might and Magic 1-5 games (the ones that use DOSBox) on Linux.
In my examples I'm setting up World of Xeen, but the same applies to them all.

Make sure you have DOSBox installed (most of the popular distros include it in their repositories, e.g. on Ubuntu you can install it using "sudo apt-get install dosbox", similarly on Fedora "su -c 'yum install dosbox'", and on Arch "pacman -S dosbox")

Firstly, you'll need the extracted folder (i.e. the one created by the GoG installer) that has the actual game executable and such inside. To do this, either run the GoG installer on Windows or on Linux using WINE, and copy the entire game folder (by default located in C:\Program Files\GOG.com\Might & Magic VI Limited Edition\)

So, for example if you're setting up World of Xeen, copy the "Might and Magic 4-5 - World of Xeen" folder.

Copy the game folder somewhere in your home directory (I like to store my in ~/Software/ to keep things organised) and rename it to something command-line friendly (e.g. "xeen")

Now you can run the game by opening up a terminal and running the commands:

cd ~/Software/xeen
dosbox -conf dosboxMM4-5.conf -noconsole -c "exit"

To make this even easier, you can put this in a little script, and even have it stored in a directory on PATH so it can be ran like other programs.
I have a file named "xeen" stored in ~/bin with those two commands in, which has executable permissions (which can be added by running "chmod a+x xeen") and so can be run like any other program, by simply typing "xeen" into a launcher or terminal.

[Edit] Changed commands to be in italics for readability