I have an LCD that requires level shifting before I can connect it to my PC. I purchased a Sparkfun PRT-00133 RS232 level shifter for this very reason, but it doesn't have any mounting holes (and the LCD doesn't anyway).
The solution I came up with was to print a carrier, and then I could attach the PCB to it, and then double stick tape everything to my LCD. The PCB attaches to the carrier via the included jackscrews.
Print this part with the DB9 end facing down, so that you can take advantage of the draft I added that precludes the need for support material (i.e. you can print this on a MakerBot). It's also better to not waste ABS anyway, right?