1. From the menu bar, click Image->Resize (or just Ctrl+r).
|Step 1. Go to the Resize menu|
2. Locate the "Resampling" drop-down menu at the top of Resize window. By default, the option selected is "Best Quality".
|Step 2. Click the Resampling option|
3. Choose the "Nearest Neighbor" option. Set your width and heights. Then click "OK".
|Step 3. Select "Nearest Neighbor" resize option|
You now have a large image with the pixelation still intact.
How did I find this out? Experimentation (aka guess and check). Good thing there were only four options there to choose from. ;)
UPDATE: A few days later, I have now written a follow up to this with more image comparisons and reasons why you may want to keep pixelation on an image when resizing.
~ Danial Goodwin ~
ps - The image I used in my screenshots used to be 34x32 pixels, then I scaled it up to be 1000 pixels wide. Then, I added the gem's shine (which isn't pixelated).