I've been thinking if there's a way to turn VSync on in both games. The screen tearing isn't really an issue, but it would be nice if I could get rid of it. Is there any way to do this?
Thanks in advance! :)

Find the games folder for the game your having problems with and look for a .conf or .ini settings file for the game. Open it with notepad, if your on vista or win7 and you installed this game to program files you will need to launch notepad as an administrator first and then open the .conf or .ini.
Once you have it open find the [vsync] section and change vsyncmode=off to vsyncmode=on. If that doesn't work you can try using vsyncmode=force instead. Then change the vsyncrate=75 to whatever rate your monitor runs at. I'm also not sure but changing the first bit to host might get it running on your monitors refresh rate as well.

Nope, didn't do it for me. I tried on, force and host, and I even changed the vsyncrate to my monitor's refresh rate.
Anyway, thanks for the help. As I said, not a big issue.
Btw, I saw this on the config file: "# vsyncmode -- Synchronize vsync timing to the host display. Requires calibration within dosbox." So maybe I'm missing something there.

I guess you could check the dosbox folder inside the earthworm jim folder for a .conf file and see if you can change vsync settings to match that.
If that doesn't work if you have an nividia graphics card you can force vsync settings on that in the manage 3d settings menu. I'm fairly sure ati cards will have the same thing.