It's fairly simple really.
Download Moonshell2 and extract.
Copy moonshl2.nds and moonshl2_DirectBoot.nds to your uSD (any directory)
Copy the moonshl2 directory to the root of the uSD
Create the following folders in the root of the uSD: 'moonmemo' & 'dustbox'
Put the uSD in the AceKard
Put the AceKard in your DS
Turn the power on
Press any key to bypass the Health & Safety Warning if you have official DS FW
Press A if you have your DS FW set to Manual
Browse to the location of moonshl2.nds and moonshl2_DirectBoot.nds
Run moonshl2.nds. If it fails, run the other one.
A screen will appear with some options. After that, you should be good to go.