Pardon me, I read the post incorrectly.
Here, I downloaded dosbox just now again and read the couple of Q/As at the beginning and here's the scoop....I don't know if you've read and already tried all this stuff, but just bringing it to your attention if you have not:
Q: I can't type \ or : in DOSBox.
A: This is a known problem. It only occurs if your keyboard layout isn't US.
Some possible fixes:
1. Switch the keyboard layout of your operating system.
2. Use / instead.
3. Open dosbox.conf and change usescancodes=false to usescancodes=true.
4. Add the commands you want to execute to the "configfile".
5. Change the dos keyboard layout (see Section 7 Keyboard Layout).
6. Use ALT-58 for : and ALT-92 for \.
7. for \ try the keys around "enter". For ":" try shift and the keys
between "enter" and "l" (US keyboard layout).
8. Try keyb.com from FreeDOS (
http://projects.freedos.net/keyb/).
Look for keyb2.0 pre4 as older and newer versions are known to
have a bug in the loader routines.