Of course it's possible!
If you're asking whether it's easy, then that's another question.

If the modder added new art defines [that re-add art from the base game] rather than reusing the old ones, then it's somewhat easier.
You have to add the new files to the mod's folder, and add references to all of the new files in the .modinfo's <Files> section. You can leave the md5 part out, and just use <File import="1"></File>. The import="1" is important, it adds the files to the Virtual File System.
Then you need to change the art defines to point to the appropriate .fxsxml file.
If you're comfortable with ModBuddy,
this tool can turn a mod into a ModBuddy project, which could make your job easier. In this case, after you add the new files, make sure to set them to VFS=true.
I assume we're talking about one of Cryptic's and Glacierheart's mods again. If it's, say, Resources Expanded, they did add new art defines for their new resources, and you're going to edit Database\REX_Art.sql.