It looks like the sparkfun crystal is slightly bigger than the stock launchpad one. It's also a through-hole part rather than SMT. I think it would be possible to push the leads through the plated through-holes on either side of the pads used by the stock SMT crystal. Then you could solder the two wires from the back of the board, which might be easier than surface mounting.
The body connection can probably be made with the sparkfun crystal even though it doesn't have a flat underside. Having said that, the body connection is not essential. It grounds the case, which helps to shield against any interference. It should still work just fine without it, and it's better to leave it unconnected than to overheat the crystal if you're finding it awkward to solder.