Okay, take a look at the link below on point 4.2:
http://help.sap.com/businessobject/product_guides/sbo41/en/sbo41sp3_bi_custom_en.pdf
It looks like you need to start by getting the template from your installation package, under the \Collaterals\Tools\CustomizationTemplate\ folder.
After that, you will have the files you need, and then be able to continue with the customization.
/Kris