Adding feature stapling to any custom site tempalte.
1. Add a new feature with feature stapling xml
2. Add following xml to element.xml file for that feature.
<?xml version="1.0" encoding="utf-8"?>
<Elements xmlns="http://schemas.microsoft.com/sharepoint/">
<FeatureSiteTemplateAssociation
Id="2B78C8DE-4C07-4a18-A6A6-E9FE1AB7EE30"
TemplateName="TestSiteTemplate#0"/>
</Elements>
Notes-
1. Please make sure that the newly added feature is part of the custom web template.
2. You can find out template name and ID (Ex. TestSiteTemplate#0 )in the xmls given at following path.
C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\14\TEMPLATE\1033\XML