[Twisted-Python] Process without fork() exec()

Hello, im trying to make Twisted run on an embedded system which doesnt support fork() and exec(). Lets say i have a function os.writeLine(), which just makes a prinft("foo") on the stdout. I implemented writeLine() in the posixmodule.c of the python so os.writeLine() would make the work. Now i would like to create a Process (from buildbot ShellCommand) which just calls writeLine() and gets the stdout of it (foo). No fork, no exec .. std are standards: 0,1 and 2. since i tried to understand the class Process(_BaseProcess) in (twisted/internet/process) and i couldnt resolve my problem alone, i would like to get some help so could someone please point me to the right direction .. best regards ..