There's also the cheap, pathetic approach:
1) Take a screenshot (Ctrl + Print Screen)
2) Open up some image program, like Photoshop
3) Ctrl + V to paste what your computer just took a screenshot of
The sweet thing is, in Photoshop, if you create a new document, the program checks to see if you have ANY image currently copied, and will create a canvas the SIZE of what you have copied, so when you paste your image, it will fit to the canvas.
4) Save as a .jpg (or other image format)
5) Import into Maya as usual
Please note, however, that this is only good for relatively small image planes; if you've constructed some gigantic skyscraper or mansion, this will be a much more agonizing process, as you might have to zoom into the scale you want in CAD, take multiple screenshots, paste them, and "maneuver" them around like pieces of a jigsaw puzzle.