You can easily create wallet sized images on a 4x6" print using Adobe Photoshop Lightroom. Download the Wallets on 4x6 template below and follow the instructions to create 4up wallets on a 4x6" print. You can then submit the JPG's saved as a 4x6".
1. Open Lightroom and click on the Print tab on the top.
2. Right-click the User Templates tab on the left and select "Import..."
3. Import the a "Wallets on 4x6.irtemplate" file (download below).
4. Select the "Wallets on 4x6" template and click on Printer... at the bottom right.
5. Select "Save PDF to folder as JPG"
6. Save the JPG file(s) in your favourite location.