We’ll soon (<1 week) be releasing a public beta of the next release of GadgeteerCore on http://gadgeteer.codeplex.com/ . The big change is NETMF 4.2 support, but also the GadgeteerHardware.xml and msm.wxs template files have been updated to document this requirement (custom assemblies) better. You’ll have to instantiate a new module template to see this. The readme.txt file in that template also includes detailed updating instructions to help you make your modules compatible with NETMF 4.2 mainboards as well as 4.1.
The specific answer is that you should include the required assembly in (NOT ) in gadgeteerhardware.xml, and the designer will automatically add a reference to it when your module is used. You also need to include the assembly’s files (dll, pdbx, etc) in msm.wxs (the new template provides handy commented-out examples to uncomment :)) I believe this should work with the existing release too.
ExtraLibrariesRequired and LibrariesProvided allow for modules to indicate compatibility with other modules/mainboards enabling design-time error messages. (I’d like to change these names but we would break the schema for existing modules if we did, so we won’t).
@ Pete - we thought about but didn’t fully address the problem of optional extra assemblies. I suspect that if you drag the module in, it will add references but then you can remove them, though I’m not 100% sure that they wouldn’t get re-added by the designer under some circumstance. Something for beta testing if you have a chance