Yes, I am using Scribus 1.4 rc5.
I go to file pull down menu > down to External tools, there chose Gimp. I am using Gimp 2.6 on Windows XP Pro. I have not had any problems with it. I have been able also to use Inkscap from that menu and create a vector file.
But I have read somewhere that there is and update to Gimp, 2.8 but not able to find it, and that, so I am tolled can produce CMYK files.
Wena