If you look into coreresource.arc and look at all of the .stp files in stages/. Those files define the spawn position for the player. The very first variable (after the list of strings) which is of 12 length (C hex) is the position where the player spawns. Second variable (for the mercs maps) define the second spawn point, while the others probably define versus spawn points). For normal stages there's usually 2 spawn points, obviously for Chris and Sheva.

s503.stp
24 55 D1 C2 94 A3 38 40 52 80 E4 BF - Sheva's spawn point

-One full entry in stp should be 0x40 length