Great news. Mr Smealum released the alpha payloads for Otherapp, which allows Soundhax to work on 3DS new firmware 11.3.0-36. Soundhax is really easy way to access to homebrew launcher.
So how to use Soundhax on 3DS 11.3? Here is the soundhax user instruction. If you have installed soundhax before, you just need to replace the otherapp file and new soundhax.m4a compatible with your 3DS firmware version. We have tested on 3DSv126.96.36.199-36J and there is no problem with Soundhax on 3DS 11.3.
Besides, *hax 2.9 alpha payloads has been updated for 3DS new firmware 11.3. Now Ninjhax 2.9 can works on 3DS11.3.