Alright, time to give you a detailed explanation. Remember the AP + Randomized patch is hypothetical, and I'm not sure if it'll work.
1. Randomize your game, then apply the AP patch. If that doesn't work, AP Patch first, then randomize. [This is the hypothetical step that I do not guarantee will work. Use
RetroGameFan's DS-Scene Rom Tool to apply the AP Patch. If the patch is not included, look through
here. If you'd like to use cheat codes, add
this to the layers upon layers of patches you'll be adding.]
2. Then, extract the files required to make forwarders run from
this thread to get nds forwarders working, and download
Forwarder3-DS.
3. Insert the SD card into your PC, and open Forwarder3-DS. Select the target card you're using, in this case it'll be from the 3DS SD card, as you're looking to "install" the rom as a cia. Then, enable "Automatically set ROM path"
4. Browse your SD card for the ROM file using Forwarder3-DS, and select them.
5. Click the Floppy Disk button to save, and transfer the .cia file generated to your SD card.
6. Install the CIA forwarder
7. Play SoulSilver.