Now before everyone's going to say double-spending is impossible i want to say that i want to make a double-spend attempt means one transaction will confirm and one will drop.
Right.
Double-spending is impossible
Double-spend attempts are possible and sometimes network confirmes second transaction, not the first one
but that was mostly a poor luck because Eligius and BTC Guild have forgotten about my first transaction which had 0 fee.
Every node cleans its memory-pool from old unconfirmed transactions (usually small transfers with zero-fees).
The difference is that some nodes keep such transactions for several days, Eligius does not keep zero-fee low-priority transactions at all.
What i want to make is either push two transactions at exactly same time that will both get relayed and get on the network but in the end only one will confirm or either discover a node which relays double-spend tx's
Every node which does not keep transactions in memory pool relays the transactions which you call "double-spend".
and will allow me to double-spend that transaction at any time.
You have to find not a relaying node, but a miner which uses "replace-by-fee" patch.
I do not know about such miners, but this is allowed by bitcoin network and bitcoin protocol.
As far as I know, biggest mining pools do not use this techinque.
It has been moved to
http://respends.thinlink.com/