I do not believe so. The SCDS2 extra RAM uses a significantly different interface and would not be accessible by the DS processor (which is the one OperaDS uses) in the same way Slot-2 RAM is. Furthermore, OperaDS relies on the high bandwidth of the parallel GBA port, which offers speeds Slot-1 cannot provide. Making it compatible would require significant changes to the program architechture, which border on impossibility without access to the soruce code.
Keep in mind that this is nothing more than an educated guess, I do not have the same insight into the DS/GBA/SCDS2/Opera internals that homebrew or official developers might have.