I recently bought the Acer Iconia W700 which is a Windows 8 tablet and i had the same problem. I'm not a native english speaker, so i'm sorry if there are mistakes in the text.
I found two solution that worked for me.
Solution one was to connect a USB mouse into the device before starting DOSBox and it worked from there with the touchscreen even if I took the USB mouse out of the device. It does require the USB mouse everytime you start DOSBox.
Solution two was to download the D-fend Reloaded frontend and when i started the default Dosbox profile in there I got a "Starting DOSBox failed" messagebox. At the bottom there is a setting for all profiles and there is "SDL videodriver" and it shows Direct X (default). When I click it I can choose "Win DIB" instead and with that setting DOSBox launched normally. I couldn't find that setting anywhere else in the program.
The touchscreen doesn't quite work properly with full screen, but in windowed original size it seems to work (mouse goes where i click on the screen). I haven't had time to test if some setting will improve this. My GoG.com version of Master Of Orion 2 seemed to work with default settings from D-Fend profile wizard (played for 5 minutes).