Brace under the back of the trailer with cribbing before you try and put the safe on the trailer. If you do not, the trailer might break loose from the hitch and try and do a backflip in you face. Make sure the safe is in the middle of the trailer and the trailer is properly balanced before you remove the cribbing. You will need a several ton jack and a number of 4x4 and 2x4 peices to do this.
If you are moving this on a concrete floor go and get yourself some 3/8 inch solid rod at the local steel company and have it cut to 28 to 29 inche lengths. This will roll so easily that it can be scary. You will need about 6 rollers like this. Go slow and do not push hard until you have a feel for how easily it moves. (You could push it right off the rollers and will have a heck of a time putting it back on them.) You will need several large crowbars and hardwood chocks, pine will just compress and wont work properly.
If this it going into your house go and get some 1/2 inch plywood cut to about 28 inch widths to fit thru the doors. This will protect the floor/tile/carpet. Also a single layer of cardboard under the plywood will provide additional protection. If you use the plywood, use 3/4 inch iron water pipe cut to about 28 inches the 3/8 inch rods will dig into the plywood.
Turning corners? Place the rollers at a 45 degree angle and roll the safe and twist at the same time or get one roller under the safe and balance in the center and twist.
Getting over door ways and sills. Crib the safe up into the air on 2x4s one side at a time. Don' scimp on cribbing, if it looks like it could use another board it does. Don't go higher than you need to clear the sill. A solid board thru the door braced throughly will let the rollers roll thru the door. Hard to describe the process.
Going up or down stairs? Hire someone!! They will have the necessary tools and skills not to get hurt. Call your local safe/locksmith tell him what you want to do and get a price. You can always earn enough to pay him, if you are hurt you are out the doctor bills and out of work.
Do I know of what I speak? How about laying down a 12,000 lb vault door and moving it 200 ft to the trailer outside, putting it on the trailer and then unloading it at the dock.
I will admit it took the two of us almost 8 hours. Only one of several jobs like that I have done or been involved in.
Marc after looking at all to the things you will to buy to do this job safely, the cost of the materials and tools will probably be equal to what the local locksmith would charge you to put the safe in your house. That will be my suggestion. Be safe (not a pun) something that heavy will hurt you faster than you can sneeze.