That camera has a non-removable lens, so you are stuck with the 28-116mm lens the camera came with!
However, with the addition of a filter tube adapter you can add converter lenses to the camera. Raynox has a 2.2x converter that would give you a maximum tele of 255mm BUT WITH VIGNETTING. They also have a 1.54x that doesn't have a problem with vignetting at maximum tele:
http://www.raynox.co.jp/english/digital/e5400/index.htm
If having 70-300mm is important to you, suggest you buy a different camera that has that capability. There are several ultra zoom cameras on the market that have a 38-380mm range, some even have more wide or more tele.
