If it's the folder is on the boot drive then the only way to accomplish this is with a combination of groups and ACL's as far as I know. There may be other ways but this is the one I know.
You say the folder is on the network but is on the boot disk, how are you setting this up and are the users accessing this all from Mac's? And they all have accounts on this Mac?
In a nutshell you would setup a group that all the users needing to access the folder belong to and then setup the ACL on the fodder so that all member's of that group will have full permission to whatever is in the folder.
So first in Users&Groups create a group for this and add all the users who need access.
The do to the folder and change its group to the group you created and change its mode to 775 (or 770 if you don't want anyone else having even read access on the folder)
Then enter this
sudo chmod -R +a "GroupNameCreated allow delete,chown,list,search,add_file,\
add_subdirectory,delete_child,file_inherit,directory_inherit" folderToChange
Now the weird thing is if you look at files in the folder they will appear to have the normal Unix mode of 644 but anyone in the group will have read, write and delete permission on the items in the folder.
I suggest you play with this on a test folder and seeing if it meets your needs before changing the working folder.
Also this will not change anything already in the folder it only applies to newly created files/folders
regards
