You need a tool called eNDryptS Advanced.
*I will not help you in any way to use that tool and it´s usage and any damage you may or may not, find on using it is not my fault in any way. Ok ?
Remember, this emulator is far from being perfection so please do not complaint about it. It is still in development and he said that he is currently focus on 2-D, 3-D and sound right now. The ds card is still in partially emulated and won't be fully until then.
P.S. Do not forgot that you will need NDS BIOS and firmware.bin for it to works. Do not asked for it because this is against the rules.