{
    "encSeed":
{         "encStr":"U2FsdGVkX186DSL2uPp1vZO......","iv":"1cb31568e......","salt":"3a0d...."},
    "encHdRootPriv":    {"encStr":"U2FsdGVkX19FA0tZsR......","iv":"da5e226....","salt":"45034...."},
"hdIndex":1,
"encPrivKeys":{
"92f2f6b0cc1.......:{"key":"U2FsdGVkX183.....","iv":"5ec1968....","salt":"371302....."}},
"addresses":["0x92f2f6b......"],"keyHash":"f1af35a6222......",
"salt":{"words":[-918769374,1616628770,1822257817,983741528],"sigBytes":16}}

npm install eth-lightwallet
node
>var lightwallet = require("eth-lightwallet")
>var upgrade = require("eth-lightwallet/lib/upgrade")
>var jsonStr='contents of ./app/users/admin/*.json file'
>var newJSON
>upgrade.upgradeOldSerialized(jsonStr, , function(err, tmpJSON) {newJSON=tmpJSON;console.log(newJSON);});
>keystore = lightwallet.keystore.deserialize(newJSON);
>var derivedKey;
>lightwallet.keystore.deriveKeyFromPasswordAndSalt('', '', function (err, pwDerivedKey) {derivedKey = pwDerivedKey;});
>var addresses = keystore.getAddresses();
>keystore.exportPrivateKey(addresses[0], derivedKey);

npm install eth-lightwallet

node

> var lightwallet = require('eth-lightwallet')

> newJSON = lightwallet.keystore.upgradeOldSerialized(JSON.parse(fs.readFileSync('lightwallet.dat')), <password>)

> keystore = lightwallet.keystore.deserialize(newJSON)

> keystore.exportPrivateKey(<address>, <password>)
'7...bla'

geth account import /path/to/damn_private_key