Verbatim from the Admin Guide -
To upgrade from a previous version of DLO to Symantec DLO 8.0
1 Run setup.exe to start the installation wizard.
2 Click Next.
3 Read the license agreement, and if you accept the terms, select I accept the
terms in the license agreement.
4 Click Next.
5 Proceed with the installation.
Note: During the installation process, a dialog may appear indicating that the
SQL services failed to start. Click Ignore to continue.
6 When the installation is completed, click Finish.
There is no need to upgrade to 7.5, since upgrade from BE 2010 R3 is supported. Schema upgrades are not required when upgrading from 2010 R3 to 8.0