To start, I am providing option 78
--Option 78 broken down...
                                   Dec to Hex
You have to do 01 then each value broken out... c0=192 -- a8=168 -- 2e=46 -- 03=3
  option 78 instance 0 hex 01c0a82e03  
-Config that we used on a S to be a DHCPserver 
S3 Chassis(su)->show run
!configure terminal
 interface vlan.0.196
  ip address 10.58.196.241 255.255.255.0 primary
  ip dhcp server
  no shutdown
  exit
!
# Static routes configured on routed interfaces
 ip route 
0.0.0.0/0 10.26.196.1 interface vlan.0.196 1
!
 ip dhcp send-all-options
 ip local pool Extremenetworks 10.58.196.0 255.255.255.0
  exclude 10.58.196.1 20
  exclude 10.58.196.241 1
 exit
 ip dhcp pool Extremenetworks
  bootfile dhcpboot
  domain-name 
Extremenetworks.com
  lease 100 0 0
  option 78 instance 0 hex 01c0a82e03  
  default-router 10.58.196.241
  dns-server 1.1.1.1
 exit
Jason