1. You need both libjson and mia packages.
2. Packages that mia needs:
  a. iptables-mod-ipopt 
  b. kmod-ipt-ipopt 
  c. iptables-mod-nat-extra 
  d. kmod-ipt-nat-extra 
  e. libpthread
3. Choose the appropriate ipk file for your openwrt firmware
4. Modify /etc/init.d/mia script, change the WAN_IF and LAN_IF variables to your wan and lan interfaces if needed.
5. Enable mia initscript
6. Access your router's UI: http://<ip address>/mia/index.html