1) Sikuli can use Python modules syntax. I used it in my practice.
My old module was started like this:
# import
import sys
sys.path.append("/Program Files/Sikuli")
from sikuli.Sikuli import *
# some Sikuli functions further.
Then I imported my module like Python module in Sikuli/Python main routine and used it's functions. So you can put your TC in modules and call them from "Main" module.
2) There was some works on integrating Sikuli into Robot Framework, general purpose testing framework. You can Google them out.
Unfortunately, all that worked with Sikuli versions before 1.0 , and I just don't know how it is going now (there is one developer on Sikuli now and things don't go smooth). In general, the answer is "yes, you can" (other way or another), but I can't give clear full details now.