I have a LK90TV with smartmedia slot, and I have gotten it to work, with the following steps:
1. Make sure the smartmedia card is 3.3V instead of 5V.
2. Make sure it's between 16MB and higher, I tried a 3.3V 4MB card, but cannot be formatted by LK90TV. I bought a 64MB 3.3V and it works.
3. Format it with Casio, and if successful, will empty it and left it with a Casio_MD folder.
4. download MIDIs from Internet
5. use Casio SMF Converter(free download from Casio site) to convert the MIDI file to .cm2 format.
6. copy the .cm2 midi files to the smartmedia card, under the Casio_MD folder.
7. Insert the smartmedida card to Casio..then it should work...

The only glitch that I found is that when I put more than 200 .cm2 files to my LK90TV, it only seemed to recognized from 000 to 199, and not beyond.... Ming