I think the only thing you can do to configure the DHCP superscope on the router is the following:
Declare your primary dhcp pool as you would normally do, then decalre a secondary dhcp pool, and configure as much as you need.
Then assign secondary ip addresses on the interface connecting to your lan and add the " ip dhcp smart-relay" command.
With this, the router will start giving out ip addresses from the primary, and when it runs out of them, it will start giving out from the second, and so on.
For example,
Lets say you have networks 10.1.1.0, 10.1.2.0 and 10.1.3.0
First you declare your ip pools:
ip dhcp pool rollover
network 10.1.1.0 255.255.255.0
dns-server {ip of dns 1} {ip of dns 2}
default-router {ip address}
lease {days} {hours} {minutes}
netbios-name-server {ip address}
domain-server {domain, i.e. cisco.com}
ip dhcp pool rollover2
network 10.1.2.0 255.255.255.0
dns-server {ip of dns 1} {ip of dns 2} <---- same as above
default-router {ip address} <--------- same as above
lease {days} {hours} {minutes} <---- same as above
netbios-name-server {ip address} <---- same as above
domain-server {domain, i.e. cisco.com} <----- same as above
ip dhcp pool rollover3
network 10.1.3.0 255.255.255.0
dns-server {ip of dns 1} {ip of dns 2} <---- same as above
default-router {ip address} <--------- same as above
lease {days} {hours} {minutes} <---- same as above
netbios-name-server {ip address} <---- same as above
domain-server {domain, i.e. cisco.com} <----- same as above
Then lets say that you LAN is connected via the interface Ethernet0, you
would have to assign 3 ip addresses to the interface:
Interface Ethernet0
ip address 10.1.1.0 255.255.255.0
ip address 10.1.2.0 255.255.255.0 secondary
ip address 10.1.3.0 255.255.255.0 secondary
And from the global config mode add the "ip dhcp smart-relay" command
That would be all the config needed.
