I know what you are talking about trying to set your combination on the lock. Turning that thing just a certain amount, but not to far,etc.. can be a royal pain.
As far as cable ties are concerned, I have bought them at a number of places. Places like Home Depot and Lowes Hardware (along with, I think office supply stores and the like) have them. You can get them in different sizes and quantities. You can probably get a pack of 10 or 20 for a couple bucks. If you go to a hardware store, check in the aisle where the electronic supplies and cables are.
Remember, cable ties are plastic strips with a square opening on one end and a tappered other end. The entire length of the strip has little ridges so as you pull the strip through the opening it 'locks' in place and can not be opened. I have foudn that my nail clippers do a fine job of clipping the ties open. I also make sure I pack extra's for the return trip.
Hope this helps.
Past Cruises -
Rhapsody - Alaska - May 2010
Monarch - Bahamas - May 2009
Mariner - Western - May 2007
Mariner - Eastern - March 2008