What SAP extension should I use in CMOD?(to extend a Idoc type)

What SAP extension should I use in CMOD?(to extend a Idoc type)

Hi,Experts!

I want to use a extended IDOC type to create Transaction Opptunity in CRM5.0 (because EEW structure wasn't extended automatically (using BDFG).

Now I have extended a IDOC type.After that,I have to extend a inbound function module.However I don't know which SAP extensinon I should choice in CMOD.

I doubt ALE00001.Is this right? Then, how do you assign INCLUDE to SAP extension?

If you have some infomation about this, please help me solve this problem.

Regards.