Yeah, File-->Output to file-->AVI file. Then you can select from any VFW codec that you have installed, provided there are no restrictions such as mod64 resolutions only, etc.
However I wouldn't recommend TMPGEnc for AVI encoding, there are far better programs.
PS. DivX is an MPEG4 implimentation, so I am not quite sure what you mean by DivX or MPEG4?