you also need a slot-2 device such as the ezV[as in 5] 3-in-1, supercard sd/cf/lite [anything but rumble and can play gba backups], or m3 cf/sd/lite perfect [the pro series does not support gba, so it won't work with them]. after that, you will need to patch the rom to be compatible with whatever slot-2 device you have. patch for supercard/m3.
Is there a different version or adapter so that the EVFlash 3-1 fits in the original DS? Also I don't think the M3CF works as a RAM expansion for the browser, unless a new patch has been released since I last looked.