To create a transaction, go to
https://coinb.in/#newTransaction. Put the redeem script, address and amount into the appropriate fields. As for the transaction fees, you'll have to calculate it manually. The transaction fees is the remainder of the outputs - inputs, you can use a change address if you want.
To roughly calculate the size, go to this page:
https://jlopp.github.io/bitcoin-transaction-size-calculator/. Choose P2WSH, 2 signatures and 3 public keys.
After which, go to
https://coinb.in/#sign and sign your transaction with the first private key. After that, take the signed hex and sign the signed transaction with the second private key.
Go to
https://coinb.in/#verify to see if it has been signed and go to
https://coinb.in/#broadcast to broadcast.