Here are a couple of examples taken from the cacls manual/help page.
Grant full control to User "Dean" to all files and subdirectories:
cacls somedirectory /e /t /p Dean:f Add Read-Only permission to a single file
CACLS myfile.txt /E /G "Power Users":R Add Full Control permission to a second group of users
CACLS myfile.txt /E /G "FinanceUsers":F Now revoke the Read permissions from the first group
CACLS myfile.txt /E /R "Power Users" Now give the first group Full-control:
CACLS myfile.txt /E /G "Power Users":F Give the Finance group Full Control of a folder and all sub folders
CACLS c:\docs\work /E /T /C /G "FinanceUsers":F It looks like the "/t" does the recursion into all files and subdirectories, and "/e" edits instead of replaces the access control list (permissions). You can use multiple options per command but I have been having trouble changing everything at once. Cacls looks like it wants specific groups and users as opposed to the o,g,a options.
Here's some more info from "cacls /?":
/G user:perm Grant specified user access rights. Perm can be: R Read W Write C Change (write) F Full control /R user Revoke specified user's access rights (only valid with /E). /P user:perm Replace specified user's access rights. Perm can be: N None R Read W Write C Change (write) F Full control