It seems you did mount c c:\xcoma

Do mount c c:\ instead

And then? Switched the drive around like you said (mounted the whole drive where the directory XCOMA is located instead of the XCOMA folder) ... No effect whatsoever, still get the "Unable to change to XCOMA".

I can practically taste the fact that I'm missing some really really basic thing that I haven't done... but with my own (very limited) knowledge I just don't know. I'll try loking around these forums some more, but if you could post some form of tutorial on the steps to do it I'd be mighty pleased.

Especially since following that guide haven't really helped much so far.

nvm, finally figured it out...

Placed the XCOMA folder in another folder called DSGames, which I then mounted as DOSBox's C drive. That allowed me to access the XCOMA folder as I was supposed to. Guess I can't the partition itself, but only folders inside it. Thanks for the suggestion.

hmm... I really should have registered (hate double-posting)...

CD command = Change Directory.

E.g. mount c c:\
c:\>cd xcoma
c:\xcoma\> You type in more commands here (Remember MS-DOS commands?)

I think the solution Changrey came up with is better. It's...safer and cleaner to just give DOSBox access to a subdirectory that has subdirectories in it for each game.