[SchlumPF*]

is it possible to retrieve the current origin of the player's collision box, pev_origin should not return it?

[Alka]

Get the pev_origin and add the size of player? 16 x 16 y 32 z...

[Orangutanz]

You can use:
(pev_absmin x/y/z + pev_absmax x/y/z) * 0.5

9/10 you will find that the bounding box corresponds to the origin, I think the only exception are with func_pushables.

For brush entities see (engine_stock.inc):
stock get_brush_entity_origin(ent, Floatrig[3])