The 3in1 has no filesystem, so there's nowhere to store the save file from your game. So you will have to use the Wifi version.
By "wifi connector" do you mean the USB wifi stick? If you have that, you'll need to install modified drivers before any homebrew will work on it. More details are available at http://forum.gbadev.org/viewtopic.php?t=10320
Cheers. I was wondering about the filesystem issue, but I thought I might ask since in theory we can store one "game" on the 3 in 1.....hence the curiosity. Thanks for the link re:the soft AP. I tried before and failed......might give it another go.... Anyway, cheers for your help.