Hello again, gentlemen.
I have it... Finally gave in and read the source code - <stellarium dir>/modules/HelloStelModule/libHelloStelModule.dll
and <stellarium dir>/modules/HelloStelModule/module.ini :-)
So now (at last) I can load the HelloStel module, which means I can now get on and do some coding based on it.
Thank you very much for the assistance, and for a great program. No doubt you'll be hearing from me again! Thanks to you guys and Lippo's very detailed and accurate Windows build instructions, I now know more that I ever expected (or wanted to) about MSys, MinGW, QT and non-Visual Studio compilation and linking setups.. :(
Best regards,

From: stellarium-pubdevel-bounces@lists.sourceforge.net [mailto:stellarium-pubdevel-bounces@lists.sourceforge.net] On Behalf Of Steve Ingamells
Sent: 25 September 2007 18:42
To: 'Stellarium developers public mailing list'
Subject: Re: [Stellarium-pubdevel] Compilation of Plugins for Windows,and possible restructuring of Stellarium project.

Hello Stephen, Fabien,
Thanks to both of you!
It was the folder structure. I re-downloaded the SVN Head revision, rebuilt my builds/msys folders and re-did everything. It now compiles and links... Wonderful!
Now the $64000 question, and I apologise if it's in a FAQ or somewhere I should have found it, but:
How do I get Stellarium to load the HelloStell DLL? I have the module.ini file but can't see where that should go and where it tells Stellarium what file to load... I can't see any evidence of it loading - no "Hello" across the sky, no text in the stderr console...