Online, the easiest way-
Use this online tool (you can use it offline too by saving it at appropriate location,)
Offline way, you need to install a remington binary file for scim:
Make sure you have installed latest version of SCIM.
Download this binary file - dev.remington.bin from here:
And copy it to /usr/share/scim/tables.
There should now be an entry for Remington
You can also copy
(thanks to Gora Mohanti, gora at sarai dot net for the offline tip)