In the Installation package under Admin --> tab ( in SEPM) you can find the install package for 32 bit and 64 bit, use this link to create a package and install
http://www.symantec.com/business/support/index?page=content&id=HOWTO59431
Check this thread
http://www.symantec.com/connect/forums/how-create-managed-sep-pushed-client-package-64-bit-workstation
To create the new custom install package
- In the Symantec Endpoint Protection Manager console, on the Admin tab, under Tasks, click Install Packages.
The current default client installation packages appear on the right.
- Under Install Packages, click Client Install Packages.
- Under Tasks, click Export Client Install Package.
- Browse to or create a preferred export folder, and select it.
- Select whether or not you want to create a single .EXE file. Unchecking single .EXE will export mutiple files, including an *.MSI installer file.
- Under "Pick the customized installation settings below", from the drop down menu, select your custom Client Install Setting.
- Under "Select the features you want to use", from the drop down menu, select your custom Client Install Feature Set.
- Choose "Export a managed client", then select the group to which the client will be installed. If no group has been created, select the Default Group. It is recommended to leave "Add clients automatically to the selected group" checked.
- Select the Preferred Policy Mode. The default is Computer mode.
- Click OK.