I found my notes on how to do this. This is assuming you are using geth
personal.unlockAccount(eth.accounts[0], "YOUR_WALLET_PASSWORD")
eth.signTransaction({ from: "SOURCE_ADDRESS", to: "DESTINATION_ADDRESS", value: YOUR_VALUE_IN_WEI, nonce: 0 })
The nonce is basically which output transaction you are going to perform. If its the first time sending from that address then use 0, if its the second time, then use 1. If you cannot find this then go to a block explorer and click the last transaction and it will list the nonce, so you just need to increment 1 and it will work. If you use the wrong nonce the nodes will reject the transaction.
Take that raw transaction ID and use any ETH block explorer to broadcast it.
Try with a small amount first in case you screw up, keep in mind ETH doesn't have an error checking for wrong addresses so make sure you are sending it to the correct location.
That's very useful, thanks.
however, if I have a keystore file from geth, can I simply use myetherwallet and point it to that keystore file?
one can even use it offline, generate a raw transaction, then broadcast it?