Tried looking at the readme.txt's ? open them with wordpad rather than notepad so they are easier to read.
1. Install original supercard dsone shell into your sd card.
2. Install YSMENU or TTMENU into your sd card.
3. rename original MSFORSC.NDS(in your sd card) to SC-DSONE.NDS or SCDSONE.NDS
if you want to make a primary shell as supercard shell, rename to SCDSONE.NDS.
if you want to make a primary shell as dstt shell, rename to SC-DSONE.NDS.
4. Copy MSFORSC.NDS from the multi-bootloader package into your root of sd card.
5. Optionally, Copy TTMENU.NDS in to your root of sd card. (to swtich ttmenu from supercard shell)
USAGE)
No key pressing: booting with Primary Shell. (SCDSONE.NDS or TTMENU.DAT)
X-Key pressing: booting with secondary shell.(TTMENU.DAT or SC-DSONE.NDS)
Y-Key pressing: booting with ysmenu.nds