This procedure was done on the Olinuxino Maxi.
It was connected with a wired ethernet during the procedure.
Once the WiFi is functional, the wired ethernet can be removed.
The microSD card can then be moved to another Olinuxino board such as the Micro.

Log into the Olinuxino board.

upgrade the system:
pacman -Syu

Then install development tools
pacman -S base-devel

Delete empty directories:
rmdir /usr/lib/modules/2.6.35-6-ARCH+/build
rmdir /usr/lib/modules/2.6.35-6-ARCH+/source

Install kernel source:
pacman -S kernel26-headers-olinuxino


Get the Realtek drivers from the Realtek web site:
http://www.realtek.com.tw/downloads/downloadsView.aspx?Langid=1&PFid=48&Level=5&Conn=4&ProdID=277&DownTypeID=3&GetDown=false&Downloads=true

I downloaded RTL8188CUS (the one showing up on lsusb)
If you choose RTL8192CU you get the same file

The file comes as a zip file:
RTL819xCU _USB_linux_v3.4.3_4369.20120622.zip

Assume you downloaded it to your workstation.
Unzip the file.
Inside there is a folder called driver with a file inside called:
rtl8188C_8192C_usb_linux_v3.4.3_4369.20120622.tar.gz

Copy that file to the Olinuxino target:
scp rtl8188C_8192C_usb_linux_v3.4.3_4369.20120622.tar.gz root@ip_addr_of_Olinuxino:/root

log into Olinuxino
cd /root
mkdir driver
mv rtl8188C_8192C_usb_linux_v3.4.3_4369.20120622.tar.gz driver
cd driver
tar xzf rtl8188C_8192C_usb_linux_v3.4.3_4369.20120622.tar.gz
cd rtl8188C_8192C_usb_linux_v3.4.3_4369.20120622
vi Makefile

Change the line:
CONFIG_PLATFORM_I386_PC = y
to
CONFIG_PLATFORM_I386_PC = n

Below it add the line:
CONFIG_PLATFORM_ARM_iMX233 = y


find the block:
---------------------------------------------------------
ifeq ($(CONFIG_PLATFORM_ARM_PXA2XX), y)
EXTRA_CFLAGS += -DCONFIG_LITTLE_ENDIAN
ARCH := arm
CROSS_COMPILE := arm-none-linux-gnueabi-
KVER  := 2.6.34.1
KSRC ?= /usr/src/linux-2.6.34.1
endif
---------------------------------------------------------
Below it add the block:
---------------------------------------------------------
ifeq ($(CONFIG_PLATFORM_ARM_iMX233), y)
EXTRA_CFLAGS += -DCONFIG_LITTLE_ENDIAN
ARCH := arm
CROSS_COMPILE := /usr/bin/
KVER  := KVER  := 2.6.35-6-ARCH+
KSRC ?= /usr/src/linux-2.6.35-6-ARCH+
MODDESTDIR := /usr/lib/modules/2.6.35-6-ARCH+/kernel/drivers/net/wireless/rtl818x
endif
---------------------------------------------------------
Save and exit:
:wq

make clean
make
rmmod 8192cu.ko  (not really needed)
insmod 8192cu.ko
make install

Verify that the driver has been installed:

[root@alarm wireless]# ls -l /sys/class/net
total 0
drwxr-xr-x 4 root root 0 Aug 14 16:55 lo
drwxr-xr-x 4 root root 0 Aug 14 16:55 usb0
drwxr-xr-x 5 root root 0 Aug 14 16:43 wlan0

wlan0 is the new driver

  reboot

Make sure you can see both usb0 (ethernet) and wlan0 on all the following:
  ifconfig
  ls -l /sys/class/net
  iwconfig

you may need to bring the interface up manually:
  ip link set wlan0 up

scan for access points:
  iwlist wlan0 scan   
  cp /etc/wpa_supplicant/wpa_supplicant.conf /etc/wpa_supplicant/wpa_supplicant.conf.original
  wpa_passphrase myssid "my_secret_passkey" > /etc/wpa_supplicant/wpa_supplicant.conf

Associate with access point according to the encryption type:
Encryption                Command
No Encryption             iwconfig wlan0 essid "linksys"
WEP w/ Hex Key            iwconfig wlan0 essid "linksys" key "0241baf34c"
WEP w/ ASCII passphrase   iwconfig wlan0 essid "linksys" key "s:pass1"
WPA                       wpa_supplicant -B -Dwext -i wlan0 -c /etc/wpa_supplicant/wpa_supplicant.conf

Verify association:
iwconfig wlan0

Assign IP address:
  dhcpcd wlan0                            (dhcp)
or                                       (static)
  ip addr add 192.168.0.2/24 dev wlan0
  ip route add default via 192.168.0.1


-------------------------------------------------
To set up automatically at boot:
  pacman -S netcfg
  pacman -S wpa_actiond
  pacman -S ifplugd

  cp /etc/network.d/examples/wireless-wpa /etc/network.d/my_wifi_network
  cp /etc/network.d/examples/ethernet-dhcp /etc/network.d/my_eth_network

  vi /etc/network.d/my_wifi_network
configure all parameters

  vi /etc/network.d/my_eth_network
configure all parameters (make sure you change eth0 to usb0)

You can have multiple profiles (e.g. for roaming, etc.)

To manually connect a profile:
  netcfg my_wifi_network
To manually disconnect a profile:
  netcfg down my_wifi_network

There are 3 daemon options for configuring networks at boot time.
  1. network -- the original setting. don't use that since we're using netcfg
  2. net-profiles
or
  3. net-auto-wireless  and net-auto-wired
This procedure is using the last option.

vi /etc/rc.conf
Look for DAEMONS=(..)
delete network and add:
  net-auto-wireless  and net-auto-wired

vi /etc/conf.d/netcfg
Change to: NETWORK=(@my_wifi_network @my_eth_network)
Make sure you have the correct names for WIRED_INTERFACE and WIRELESS_INTERFACE (change eth0 to usb0)

-------------------------------------------------
Also see:
https://wiki.archlinux.org/index.php/Beginners'_Guide#Setup_wireless_network
https://wiki.archlinux.org/index.php/Wireless_Setup#Getting_an_IP_address
https://wiki.archlinux.org/index.php/Netcfg

Other commands:
ip link show wlan0