Hi guys. Here's my problem:
I installed Constructor on my desktop PC with Windows 7 Ultimate 64-bit. Installed to default folder. Since I already have DosBox 0.73 there, I didn't install the bundled DosBox. Instead, I pointed the installer to my existing installation of DosBox and it worked. Game can be played normally.
I had Dosbox 0.73 on my MacBook (OSX 10.6.2) too, so I manually copied the Constructor install folder to my MacBook and mounted the folder in DosBox. I saw that Constructor's dosbox.conf is almost the same as my Mac's DosBox config file (like cpu cycles=max, etc). The main difference is that IPX is not enabled on my local DosBox config file, while it is on Constructor's. But I figured that's not a problem.
I ran the same imgmount command to mount const.gog to D: and ran game.exe. However, an error message popped up: "Error = Unable to locate SYSTEM.INI file". Can anyone shed any light on this error? I always thought DosBox is closed from the host system. Does it have anything to do with it running on a Mac? Plus, if the game runs in DosBox, surely there are no messy registry entries on my Win7 host on my PC, are there?
PS: I have not contacted GoG.com tech support yet, because it could work on my desktop PC. It's just not working when I copied it over to my MacBook.

did you mount the right C drive as well ?

copied the Constructor folder to ~/DOS/Constructor. Then I did a "mount c ~/DOS" which mounts the DOS folder to C: when DosBox started.
The Constructor folder is truncated to "constr~1". Could that be the reason? I renamed the folder to fit the 8-char limit to "cnstrctr" as well but the same error pops up.

Hey this worked! Why didn't I think of this??
Thanks a million!!