I know many people ask this question. Recently I had a client wants me to enable AWE on the cluster which has two nodes (Active/Passive). He had only one instance of SQL Server 2000 (SP4) and 8 GB RAM and /3GB in the Boot.INI.
Add /PAE parameter to Boot.INI file. PAE is the added ability of the IA32 processor to address more than 4 GB of physical memory.
You need to install hotfix on SQL Server instance from Microsoft (http://support.microsoft.com/kb/899761) that fixs the bug "Not all memory is available when AWE is enabled".
Make sure that domain account SQL Server is running under is added to "Lock pages in memory" local group policy.
Finally we configured 6 GB for SQL Server as it was business requirements.
sp_configure 'show advanced options', 1
sp_configure 'awe enabled', 1
sp_configure 'max server memory', 6144
Note: we need to run those steps on Active node where the SQL Server instance is running on. When it failed over but the binaries are loaded on all