Step by step process of converting DAO tokens back into ETH via the WithdrawDAO using geth on the command line.

Recovering ETH From The WithdrawDAO

// Start by getting to a geth shell running "geth attach" or however you do it.
$> geth attach

Welcome to the Geth JavaScript console!

instance: Geth/v1.4.10-stable/darwin/go1.6
coinbase: 0xcbcac9e9e30f3121834bc97c8b99b6602acc6c75
at block: 1920784 (Wed, 20 Jul 2016 12:58:48 EDT)
 datadir: /home/user/.ethereum
 modules: admin:1.0 debug:1.0 eth:1.0 miner:1.0 net:1.0 personal:1.0 rpc:1.0 txpool:1.0 web3:1.0

// start by defining the DAO contract locally
> dao = web3.eth.contract([{"constant":true,"inputs":[],"name":"name","outputs":[{"name":"","type":"string"}],"type":"function"},{"constant":false,"inputs":[{"name":"_spender","type":"address"},{"name":"_amount","type":"uint256"}],"name":"approve","outputs":[{"name":"success","type":"bool"}],"type":"function"},{"constant":true,"inputs":[],"name":"totalSupply","outputs":[{"name":"","type":"uint256"}],"type":"function"},{"constant":false,"inputs":[{"name":"_from","type":"address"},{"name":"_to","type":"address"},{"name":"_amount","type":"uint256"}],"name":"transferFrom","outputs":[{"name":"success","type":"bool"}],"type":"function"},{"constant":true,"inputs":[],"name":"decimals","outputs":[{"name":"","type":"uint8"}],"type":"function"},{"constant":true,"inputs":[],"name":"standard","outputs":[{"name":"","type":"string"}],"type":"function"},{"constant":true,"inputs":[{"name":"_owner","type":"address"}],"name":"balanceOf","outputs":[{"name":"balance","type":"uint256"}],"type":"function"},{"constant":true,"inputs":[],"name":"symbol","outputs":[{"name":"","type":"string"}],"type":"function"},{"constant":false,"inputs":[{"name":"_to","type":"address"},{"name":"_amount","type":"uint256"}],"name":"transfer","outputs":[{"name":"success","type":"bool"}],"type":"function"},{"constant":true,"inputs":[{"name":"_owner","type":"address"},{"name":"_spender","type":"address"}],"name":"allowance","outputs":[{"name":"remaining","type":"uint256"}],"type":"function"},{"anonymous":false,"inputs":[{"indexed":true,"name":"_from","type":"address"},{"indexed":true,"name":"_to","type":"address"},{"indexed":false,"name":"_amount","type":"uint256"}],"name":"Transfer","type":"event"},{"anonymous":false,"inputs":[{"indexed":true,"name":"_owner","type":"address"},{"indexed":true,"name":"_spender","type":"address"},{"indexed":false,"name":"_amount","type":"uint256"}],"name":"Approval","type":"event"}]).at('0xbb9bc244d798123fde783fcc1c72d3bb8c189413');
{
   abi: [{
       constant: true,
       inputs: [],
       name: "name",
       outputs: [{...}],
       type: "function"
  }, {
       constant: false,
       inputs: [{...}, {...}],
       name: "approve",
       outputs: [{...}],
       type: "function"
  }, {
       constant: true,
       inputs: [],
       name: "totalSupply",
       outputs: [{...}],
       type: "function"
  }, {
       constant: false,
       inputs: [{...}, {...}, {...}],
       name: "transferFrom",
       outputs: [{...}],
       type: "function"
  }, {
       constant: true,
       inputs: [],
       name: "decimals",
       outputs: [{...}],
       type: "function"
  }, {
       constant: true,
       inputs: [],
       name: "standard",
       outputs: [{...}],
       type: "function"
  }, {
       constant: true,
       inputs: [{...}],
       name: "balanceOf",
       outputs: [{...}],
       type: "function"
  }, {
       constant: true,
       inputs: [],
       name: "symbol",
       outputs: [{...}],
       type: "function"
  }, {
       constant: false,
       inputs: [{...}, {...}],
       name: "transfer",
       outputs: [{...}],
       type: "function"
  }, {
       constant: true,
       inputs: [{...}, {...}],
       name: "allowance",
       outputs: [{...}],
       type: "function"
  }, {
       anonymous: false,
       inputs: [{...}, {...}, {...}],
       name: "Transfer",
       type: "event"
  }, {
       anonymous: false,
       inputs: [{...}, {...}, {...}],
       name: "Approval",
       type: "event"
  }],
  address: "0xbb9bc244d798123fde783fcc1c72d3bb8c189413",
  transactionHash: null,
  Approval: function(),
  Transfer: function(),
  allEvents: function(),
  allowance: function(),
  approve: function(),
  balanceOf: function(),
  decimals: function(),
  name: function(),
  standard: function(),
  symbol: function(),
  totalSupply: function(),
  transfer: function(),
  transferFrom: function()
}

// Do the same for the withdraw contract
> withdrawable = web3.eth.contract([{"constant":false,"inputs":[],"name":"trusteeWithdraw","outputs":[],"type":"function"},{"constant":false,"inputs":[],"name":"withdraw","outputs":[],"type":"function"},{"constant":true,"inputs":[],"name":"mainDAO","outputs":[{"name":"","type":"address"}],"type":"function"},{"constant":true,"inputs":[],"name":"trustee","outputs":[{"name":"","type":"address"}],"type":"function"}]).at('0xbf4ed7b27f1d666546e30d74d50d173d20bca754');
{
  abi: [{
       constant: false,
       inputs: [],
       name: "trusteeWithdraw",
       outputs: [],
       type: "function"
  }, {
       constant: false,
       inputs: [],
       name: "withdraw",
       outputs: [],
       type: "function"
  }, {
       constant: true,
       inputs: [],
       name: "mainDAO",
       outputs: [{...}],
       type: "function"
  }, {
       constant: true,
       inputs: [],
       name: "trustee",
       outputs: [{...}],
       type: "function"
  }],
  address: "0xbf4ed7b27f1d666546e30d74d50d173d20bca754",
  transactionHash: null,
  allEvents: function(),
  mainDAO: function(),
  trustee: function(),
  trusteeWithdraw: function(),
  withdraw: function()
}

// You may need to unlock your account (this assumes the DAO was purchased with eth.accounts[0])
> personal.unlockAccount(eth.accounts[0]);
Unlock account 0x1ceff6495e5688DB9b9cf0E55F9b3eaDC25Cb0C1
Passphrase:
true

// Recovering DAO tokens is done in 2 steps - first is the approval
> dao.approve(withdrawable.address, dao.balanceOf(eth.accounts[0]), {from: eth.accounts[0]});
"0xc7c6cd13de3dc78c8bce630f69740efe66e6f7f88edb167eb9dca4fb65e699b6"

// And the second is the actual withdrawal
>  withdrawable.withdraw({from: eth.accounts[0], gas: 100000});
"0x20f265df09ee011025b3bacbc2d7c9fd2e837967a0ac046faccac680f89d7d47"

// Now the original funding account should have ETH returned. That's it!