For an experienced technician- no problem! The task is more time consuming than it is troublesome. But not a problem. As far as relocating the register, this is also not a problem. You might want to try to get the old tech out only because since he is familiar with the project you may be able to get a deal.
To find a licensed, bonded, insured company in your area it is pretty easy to go to Google and type in air conditioning company and then your city after that, ie. air conditioning company tucson, arizona.
Take a look at their reviews also and be sure that they are a company revolved around customer service and deliver nothing but quality.

Here is a link that might be useful: Advantage Air Mechanical

Tucson man,

Can you tell me how a person that lives in New York will be helped by the company you work for in Arizona?

Comkow
The duct work is easy and the time depends on access and material.
The problem with moving the register, besides the mess is most HVAC guys are not good with drywall (patching the old hole) and especially painting, so it may take two contractors.

I wondered the same thing b/c I am not paying for his airfare to NY. DH can do the patching of the sheetrock. Thx for your response.