How to upgrade Qt installed in linux from one version to higher

Solved: I changed repository from squeeze (stable) to wheezy(testing), in wheezy latest Qt version is 4.8.1, which is perfectly suits my needs.

Using package manager I found package libqt4-dev and selected it for update. That is all, the whole process took 5 minutes.

Disadvantages: - As I run Debian on Virtual Box after changing repository I had to reinstall guest additions - wheezy is less stable than squeeze (I haven`t faced yet with stablilty problem)