Please be aware that loading games from USB drive is not(yet) possible.
Using SDHC cards up to 32GB is possible, format them to FAT32 64KB cluster size for best compatibility.
Before you use this software make sure that your Wii is backwards-compatible to gamecube games because newly released Wiis(beginning with 2011 holiday season) which are lacking the gamecube controller/ memory card ports can make no use of DML.
Our discussion thread over @GBA: http://gbatemp.net/topic/307341-dios-mios-lite/
DML compatibility list: http://wiki.gbatemp.net/wiki/DIOS_MIOS_Lite_Compatibility_List
DML SD Card speedtest: http://wiki.gbatemp.net/wiki/DIOS_MIOS_Lite_SD_Card_Speed_Test