Cisco - Configuring DHCP Reservations (manual bindings)

You can configure DHCP reservations (or manual bindings as Cisco calls them) on a router by creating a unique DHCP pool for each host that requires a reservation.

It is a hassle ... but it can be done:
Cisco Documentation

Couple of pointers I have found:

• Make sure the pools don't overlap (see my example below)
• Remember Windows machines use client-identifier not hardware-address
  
• Client-identifier is the type (01 for ethernet) plus the mac address
• You must make a unique pool for each reservation
  

Steps Required:
Router(config)# ip dhcp pool name
Router(dhcp-config)# host address [mask | /prefix-length]
Router(dhcp-config)# hardware-address hardware-address type
Router(dhcp-config)# client-identifier unique-identifier
Router(dhcp-config)# client-name name

Example (including my other DHCP pool). Note that my mac address is 0020.ed6d.####:
!
ip dhcp pool homepool
import all
network 192.168.1.0 255.255.255.0
default-router 192.168.1.1
lease 0 2
!
ip dhcp pool mypc
host 192.168.1.138 255.255.255.0
client-identifier 0100.20ed.6d##.##
client-name mypc