Software

You can find the Arduino sketch to download here:
http://code.mios.com/trac/mios_arduino-sensor/browser/trunk/Arduino/VeraGateway

You really don't need to configure anything in this sketch. Just download it and connect the Arduino to your Vera using usb-connector. Please note that only Arduino Nano module have a serial chipset recognized automatically by Vera.

Wire things up

You only need to connect the radio chip to the Arduino. Follow the instructions in ConnectingRadioModule.

Hardware - Purchase guide

This is the stuff you need to purchase to build the ArduinoGateway. Note that I've provided links to the things I bought during the development. You might find it cheaper somewhere else. Also note that you might need to buy 10x of some items to get the price specified.

1x Arduino Nano with serial interface and usb connector
​http://www.aliexpress.com/item/Free-Ship-Wholesale-IC-Parts-Integrated-Circuits-Atmel-ATmega328-Board-with-Mini-USB-Cable-Full-Compatible/704043993.html

8x Dupont cable Female->Female
​http://www.aliexpress.com/item/New-Female-To-Female-40-pcs-Wire-Cable-Line-1p-1p-Pin-Connector-20cm-2-54mm/1045212486.html

1x NRF24L01+ wireless data transmission module 2.4Ghz ​http://www.aliexpress.com/item/Free-shipping-NRF24L01-wireless-data-transmission-module-2-4G-the-NRF24L01-5PCS-LOT-upgrade-version-New/603756080.html

TOTAL PRICE: $7,99 + $0.93 + $0,6 = $9.5