Download available at
http://svsip.free.fr/
You will need a Slot1 card of some kind to run the homebrew and will need to get an sip account and configure the app to run it. This is an example of the end product.
Instructions:
Basically, you get a card that goes into the top slot on the ds (also called a ‘Slot1 Card’) and run the program. I chose an ezflash v because a friend of mine recommended but really almost any Slot1 FlashCart would work (R4 is another popular one). Chances are, it will take in a MicroSD card. You download the DS version of the program from http://svsip.free.fr/ and patch them first (These cards require a different patching technique in order to read files from the sd card. It is called DLDI patching and there are many DLDI patchers. Just google it.). Then read the readme of the SvSIP download and configure it with whatever sip account you get. Then just copy all the files to the root of the MicroSD card. Then you open the launcher (different depending on what Slot1 card you choose) and open the SvSIP program.