I don't have the battery pack, only a suggestion. I use a remote pack for a Sankyo super8 camera to power my SQAm. All you really need is the AA holder and a cable with the correct plug. Maybe you could get the bits from an electronic supplier? Battery holders are certainly available. I can't recall exactly what the plug/socket looks like, but I'm sure it's a common design. I did look for the genuine part, but couldn't find one.
The SQAm has a socket on the side of the grip. I've looked at the connection. It is a type of coaxial socket you see on devices that use a mains adaptor or charger. I don't know about the SQAi. I'm not an expert on flash, but I'm sure the SCA adapter is for use with Metz flash equipment. If you don't have the camera manual, try to look it up online. It may show a picture of the remote battery pack and where it connects.
I had a look at the SQAi manual. It has a system chart on the last page that shows two different external battery packs. One is for the camera battery. It appears to have a connector shaped like the holder for the four LR44 cells. This would be difficult to fabricate at home! The other has some sort of plug similar to what I use on the SQAm. I wonder if this connects to the motor drive when fitted. I think the motor drive batteries take over from the camera batteries when it is fitted. Perhaps someone else has this equipment and could clarify for you. Alex