See if this give you the effect you're looking for:
for each Merc you want face up:
Adjust the Pitch in the PYR to 3.14
Lower the Z axis in the POS XZY to -4
add +/- 3.14 to the Yaw in the PYR
so for instance Merc #455 changes from
0 455 POS 52.671875 4 -577.421875
0 455 PYR 0 2.294835 0
to
0 455 POS 52.671875 -4 -577.421875
0 455 PYR 3.14 -.84 0