Here is the way I work with sheet paper, for example, a custom paper like Epson Velvet, 13 x 19 (Super B)
BEGIN WITH NEW PAPER PRESET - (Create a new custom preset and calibrate)
CALIBRATE THE PAPER
1. Load a full sheet, with skew check. I load the paper in the rear tray from the front, leaning over the printer, and I line up the paper with a small groove to the right, that can't be felt with the fingers. The printer takes it in, then asks "Roll or sheet", then I check "Sheet with Skew Check".
2. The printer mostly rejects the first load, gives a message "too much skew", and since I'm still standing IN FRONT of the printer, it's easy to flip the lever (on left) UP and then position the paper at the blue lines. This requires a little practice and skill and eventually, you get it and the printer checks and rolls the paper back in, until it accepts it. If it is still misaligned, it requests you do the process again. Repeat until you get it. Once you get it, you've got it - no big deal.
3. Calibrate the sheet.
(*NOTE That if using a 13x19 sheet, the calibration chart takes up less than half the sheet, vertically. This can be used by flipping vertically (end for end) and you can run another calibration at the other end, if you wish). In other words, you can print TWO (2) calibration charts, one on each end of the sheet. This is useful if you make a mistake, or alternatively, put the sheet back in the box with the paper, and use it to update a calibration for the paper at a later date.
CREATE CUSTOM PROFILE
(Ernst and I have two ways of doing this. Please see his explanation of how to do this whole process (Calibrate and profile) with one taped sheet.)
1. Cut a 13 x 19 sheet down to 11" x 17"
2. Load the 11 x 17 sheet, same method as outlined above (see 1 and 2).
3. Go to Paper Preset management in the color center and click "profile paper"
4. Make sure you also click "Add ICC Profile"
Should be good to go.
This is a relatively straightforward process, Felix. If you try this and it doesn't work, let us know what seems to be the problem you are having.