You're going to need to resize the graphic to 960x576 first off. Then, rename the file so that it has %(4) at the end of it.
This will tell the game that your character graphic has 8 characters (even though it's technically only one character...but that's how Galv's demo is like too), each with 4 frames of animation. Since Galv's script just changes the character graphic index, it's already compatible with modern algebra's script (thankfully).