If you look at the dependencies of amule, it looks like it needs (among others):
As far as I know, none of those packages are installed on the MyBook, and each and every of those packages are rather large projects that are unlikely to get built using the "Variant 3". This variant is rather for single C program files.
(Tomas123 please correct me if I'm wrong here).
So you need what's described at "Variant 2" as last point - compilation of packages using the cross-compiler of the SDK.
As Tomas123 said - unless you are an expert just forget about cross compiling
of large packages. Even experts like us sometimes despair of large projects like this.