It might be as simple as "make", and it might be a lot more complicated. You can't know until you try. Install the SDK exactly according to the instructions:

http://repository.maemo.org/stable/4.1.2/INSTALL.txt

Then download the source, and try to build according to the instructions. It might have some libraries missing (it will be easy to tell if one of the build steps is ./configure, as this will tell you what is missing). Perhaps some those libraries are already available, but you might need to compile some of the dependencies as well.