Repackaging into an MSI using Wise Package Studio:
Download the installer.
Use the SetupCapture tool to take a "before" snapshot of the system.
Start the installer. On the "Choose Components" screen, remove the translations you don't need (it'll save disk space). Finish the installation.
If the capture picks up any files that aren't located in the "C:\Program Files\Inkscape" (or equivalent) directory, exclude those files.
In the Installation Expert, under Add/Remove Programs, check the "Hide Modify Button" checkbox. If you want a nice-looking icon in the Add/Remove Programs Control panel later, click the Browse button next to the "Display Icon" box and select the "inkscape.exe" file in the "Program Files\Inkscape" directory. Fill in appropriate information in the Support Information section.