You could actually do much the same thing. You see, what this code does is adjust some things, and then make the top layer map (The one that text and stuff goes on) semi-transparent to all other layers. If you want to read more about that, you can look at this ( http://nocash.emubase.de/gbatek.htm#lcdiocolorspecialeffects) but since you have adamently refused to learn ASM in the part, I highly doubt it will make any sense to you.
So, yeah, this could be inserted in battle, you just have to code it in somewhere, and also realize something else... The sprites aren't large enough, nor placed in the correct spots for this to look good. You would need to change their locations and everything. I also don't think the battle bg's are in the correct area either.