At the time of this writing (November 4, 2011), this custom-made installer is (almost) all you need to start using Firebird database management system from your Visual Studio 2010.
Of course, you need a Firebird server: either on your machine or on an accessible server.
This installer will install and properly configure 2 things:
(1) Firebird .NET Provider.
(2) Firebird DDEX Provider.
The 2nd one provides (among other things) support for Visual Studio 2010 Entity Framework Designer, which is exactly why I created this installer: installing the DDEX provider manually is a process which is both time-consuming and error-prone.
(To be quite honest, it took me several attempts to get it right, while the installer is supposed to do things right within just a few seconds.)
The 0.9.0.0 release works fine for Visual Studio 2010.
But, as you can see from the screenshots (and the installer itself), it is designed to be used for Visual Studio 2005 and/or 2008 as well.
If you find any bugs, please report them here.
IMHO, using a nice-looking GUI-based installer always beats messing with config files and Windows Registry.
Enjoy!