Hi Steaphany,
Katz Eye Focussing Screens provide instructions for fitting their focussing screen to the Sigma SD10. (Google for Katz Eye Optical)
I understand that they are still evaluating the possibility of a focussing screen for the SD14.
Apparently these screens transform the dslr, much better than the AF system especially for low light work. Users laud their praises, much like SD14 users!
I've seen ebay advertising an SD14 complete with Katz Eye focussing screen, so some bright spark has the know how!
Regards,
iMac