Thanks to all that replied. A couple of suggestions, the most common was to create a listener to do this. So never having created a listener, I logged a call with PTC to see if they had a sample example. This was their reply.
Upon further investigation I have found following information.
It's not OOTB function and cannot modify the IBA values in "save as" UI. Based on online help, "Save as" function is for COPY a part or CAD document, so the IBA value will be inherited. The function is still achieved with urlActionDelegate and htmltemplate, it is not supported customization technique in 9.0 anymore.
You can refer existing Enhancement SPR 1682394 for this
