We've got success! Gunnar Hjalmarsson has provided a patch that resolves the issue. I have a 64-bit system, and it works fine. I can't say about the 32-bit systems, although I expect it should work fine.
Here I am spelling out exactly what you need to do:
Add "ppa:gunnarhj/misc" to your system's Software Sources. Do this by typing "Software & Updates" in the dash and opening the tool by that name. Once it opens, go to the "other sources" tab and click on "add". In the window that opens, paste his PPA, i.e. "ppa:gunnarhj/misc". Once that is done it will ask you to click there to update the online sources. Once that is finished, then open "software updater" from the dash, and update your system. Make sure in Language Support that the keyboard input method system is still set to scim and not ibus. Then log out and log back in, and it'll be good to go.
If you want to directly read from his site, go the bug I have created on this issue. See Gunnar's post, and go to the link he gives. There you'll find more detail on the matter i.e. just what is in his ppa. But for those who are newb's, the directions I've given above will I think be easier to follow.
Enjoy using scim-m17n!