Giving IP address from specific subnet depending on MAC address

[Frederik]

I've got a DHCP server which is in a shared network consisting of two
subnets, let's say 192.168.0.0/24 and 192.168.1.0/24. So each of these
subnets is defined in dhcpd.conf within a shared-network, and each of
them has a pool defining a range of IP addresses.

Now I would like to put a part of all clients in subnet
192.168.0.0/24, and another part in subnet 192.168.1.0/24, depending
on their mac address. Unfortunately, as the host declarations are
always global, it does not help putting them within one of the subnet
definitions to let it select the right subnet.

What would be the right way to get the wanted result?
-- 
Frederik