Hi,
Essentially all the module management tool does is copy the module files held within the AMP into the correct location in the alfresco WAR file.
The installation of the module is then handled by the various module components that will be picked up when the modified WAR is next loaded.
The module management tool is implemented as a Java utility and can be found in the repository.jar. It can be called directly and the provided ModuleManagement scripts are just there are helpers to get you started.
I'd suggest trying to get the tool working in the first place, since it is the most reliable way of installing a module, but it is possible to install by hand if nessesary.
Cheers,
Roy