Well, not being really sure what you want but.. here are some hints:
You can check if the "rotten" civilians are close to your guys with
distance:
? zombies distance soldiers < 15 : goto "contagious"
You can dammage your guys progessively with
setdammage and get their dammage with getdammage.
#contagious
_damage = soldiers getdammage
soldiers setdammage _damage - 0.1
exit
(im not too sure about that script but I guess you get the idea, also, ask someone for blood stains and such, because I got no idea how to put em there)
You could also dmg the guy even more if the infected civilian touches him (bites him?).... or just convert him maybe (kill him and move some infected civilian to his position), like:
? guy1 not alive : goto "converted"
#converted
_wheredead = guy1 getpos
zombie1 setpos _wheredead
exit
I would suggest you check for an hallucination script somewhere in forum when someone is nearby a zombie and he is getting infected... that would be cool.
There is also a "drunken-like" playmove around I think, that might suit your zombies
Oh I almost forgot, to get attracted by a side... I guess you could create a move waypoint and change its position.... respect with your soldiers or guys... just keep getting your guys position every some time and update the waypoint?
I hope this helps a bit, its almost 7:00 and Im hell tired....