Open a Terminal and type curl and see if it gives you a positive answer. If you don't have the curl libraries it will be harder
If you have curl, do the following.
Open your bitcoin.conf file and put this inside
Code:
rpcuser=<username>
rpcpassword=<password>
server=1
Start Bitcoin-qt in the normal way and it will start as a server.
Open a Terminal and type
Code:
curl --user <username> --data-binary '{"method": "dumpprivkey", "params": ["<address>"] }' http://127.0.0.1:8332/
replace <username> with the username you set on the bitcoin.conf file and <address> with the address for which you want to get the private key
Press enter. It will prompt you for the password you set on the bitcoin.conf file. Write it and press enter.
Voilá, it will answer with the private key for the address.
Repeat the Terminal steps for each address you want to get the private key from.
Now import those private keys into your online wallet if it supports import of privkeys or you can import them to your friends wallet and send them to your online wallet.
You can import the privkeys on your friends Mac by opening the Debug window, pressing the Console tab and typing this:
Code:
importprivkey <private key>