ESS Portal config

Do you know where the images for Resources in the IMG are actually stored. eg

txn SPRO > Cross App Components > Homepage Framework > Resources > Define Resources... select the Add Entries option Select a picture eg COMPSPECIALIST_BUDGETING_PIC look at the details and you'll see 'money.gif'. The docs don't explain where this gif is actually located.

In the portal I can see it has a URL of http://<domain:port>/webdynpro/resources/sap.com/pcui_gp~xssutils/Components/com.sap.xss.ser.xssmenu.vc.areagroup.VcXssMenuAreaGroup/money.gif

I want to use my own image rather than SAP. How do I do this in a transportable fashion?