Ah-HA!

While scripting the securables from the database role, I found this interesting piece of code that I don't see in BOL. This, apparently, is the syntax for adding a specific permission to a table's column.

GRANT UPDATE ON [dbo].[MyTable] ([MyColumn]) TO [MyRole/MyUser] AS [dbo]

I swapped out the role name for the user group name in question and the code ran without error. Now the trick is to see if the users can actually do the deed, but I doubt they will have any problems.

WHOO! No need for roles now.

BTW, does anyone else have an issue with going into an existing database role, hitting the script button on the securables screen, and getting the error "There is no action to be scripted"? Why would it allow only scripting during the creation of the role, not afterwards?