What I need to do to run old qt3 programs on 3.5.13? I need to make some kind of aufs chrooted environment. Please, provide exact recipe of making it.

In the Trinity source tree is a directory named experimental. There are some scripts there to convert KDE3 apps to TDE. Tim and Slavek are better qualified to explain how to use the scripts. We should have a wiki article.

I don't know that pure Qt3 apps (rather than KDE3 apps) can be converted with those scripts. I presume the best approach is to install the original Qt3 in your chroot and build the app there. I haven't tinkered with that but as TQt3 normally is installed in /opt/trinity, there should be no conflicts installing the original Qt3 in /usr.

I have no idea whether the original Qt3 will conflict with Qt4.

Darrell