Tested with Asar v1.71, SNES9x v1.58, in both normal and SA-1 ROMs. I've also made a small change to prevent HDMA from being terminated before game over/time up fadeout while in levels.
This patch isn't required for insertion of HDMA effects per se, but it is recommended to fix overworld/level/game over/time up transitions that, by default, don't disable HDMA (gradients appear during moments in which the screen should be black). For advanced hackers, though, it's not very interesting, since they can manually disable HDMA through specific game modes via uberASM.
Remoderated. Tested with: SA-1 v1.32; bsnes v107.1; Asar 1.71
Didn't do any weird stuff so, it works.
Since this patch's FreeRAM area isn't meant to be changed, I made Asar detect and correct it for SA-1 by putting it in the BW-RAM area. Thanks to Stivi for checking that worked.