Before you can install HomeDrive on Mountain Lion, you need to adjust the default Gatekeeper settings so that software that is not downloaded from the App Store can be installed.
If you only allow software from the App Store to be installed, you will see a similar error message when trying to install HomeDrive (shown below):
To solve this issue, follow the instructions below:
- Open "System Preferences"
- Go to "Security & Privacy"
- Set "Allow applications downloaded from" to "Anywhere" (shown below)