A 4.8v NiMH battery pack can be bought ready-made on eBay for about $15-20, complete with plastic wrapping and pre-wired leads. Just attach the plug from the original eMate battery (and fuse if you are so inclined), and the battery problem is solved. This is a MUCH better solution than fiddling with black AA battery holders, which don't fit without modifying the plastics of your machine.
Just look for a battery pack wired 2x2 lengthwise. They are available and they work perfectly in an eMate, with excellent run times.