What about "Print Screen" - always did the job for me
To fix the "textures-not-showing-up-ingame-problem", try this:
In O2, select one of the faces (that doesn't display the texture in-game) and press "E". This will bring up the "Face PRoperties" box.
In the bottom-right corner of the box, there are three buttons (right to left) each with different icons, and a text box - probably with a line in it -- normally like "\AddonFolderName\TextureName.paa".
If there is nothing in the box, then there's your problem. To solve this, click on the far right button to bring up a box showing your directories. Navigate this until you find your "AddonFolderName" in your O2 root directory. Then find the texture you want to apply to that face and select that. Then, PBO your folder and try it out.
If there was something in the text box in the "Face Properties" pox, then look at what it says. If it says something which doesn't relate eg: "\RandomFolderName\YourTexture.paa" - then you'll need to re-direct it to the AddonFolderName folder and select the texture there.