It is possible. Just add the necessary amount of <Requires> tags to the tech. However, you need to make the change either via a XML-editor or a text editor (like Notepad++), because the included Tech Editor doesn't support it. There is also a small issue with the UI, as it shows the unlocked tech behind all prerequisite techs, but that is purely cosmetic.
It might be possible to fix the UI issue, but I never tried to do it. As far as I know, you need DesktopX to be able to modify the UI, and I don't have it.
