I purchased a 7250 on the Bell network from Ebay several weeks ago. The phone Number on the unit is a number from another province. I would like to switch the number to my Aliant cell phone # so I can receive calls on it.

Is this something I can do myself? I'd prefer to do it myself if possible.

TIA,

You need to contact your carrier and have them change the ESN on your wireless account to that of the new 7250. Once the ESN change is completed on the carrier's side, then you must program the phone so it's provisioned on your wireless account.

So... no, this is absolutely not something you can do by yourself.

Correct. Unlike their GSM counterparts, CDMA devices can only be activated by the carrier.
Aliant is usually pretty good with doing it as long as they're Bell/Aliant devices.