It is possible to install the version 3.0 over a full Windows version 2.76 in the same directory, and run the 2.76 version apart from the 3.0 version. But you can also install the 3.0 version of SkyCharts only. You can download the last stable (still Beta) version from SourceForge. You also could try the latest development version from here.

Run the installer file skychart_3.xxxxx.exe, to install SkyCharts in your prefered directory (i.e. C:\Program Files\Ciel)

At any time you can start the version 3 with skychart.exe, or the 2.76 version with ciel.exe