^-- In this case(Which is fully true), the script can both capture the screen shots and glue them into a sprite sheet(strip) with bmap_create and bmap_blit.

http://www.conitec.net/beta/abmap_create.htm
http://www.conitec.net/beta/bmap_blit.htm

Again alpha can be handled at runtime with a color key or maybe there is an engine bmap function for replacing a color on the strip with a 32 bit alpha before saving it out.