Hi
For this landscape first you need to create CMS and Audit database on SQL Server.Then you need to create the System DSN for CMS and Audit database on server 2 and 3.
You need to start with server 2 and select the custom/expand installation.Select the core services and uncheck the web components & webi and crystal services depend on the installation requirement from this server.
There is no need to perform full installation on server1 and disable the services.
Once installation will complete on server 2 then start with server 3 and select the custom /expand installation and you will get the option in the installation to select option "Expand an existing SAP BusinessObjects BI platform deployment".
Once server 2 and 3 installation will complete then you can install web tier or crystal services on different box.
If you have specific questions then let me know.
Amit