Gerd,
Sorry for the delayed response. The simplest way to install MyEclipse, is, of course to use the offline installers. Did you try using this? You can get it here: http://myeclipseide.com/module-htmlpages-display-pid-4.html
The custom installer is applet based and therefore susceptible to problems associated with applets. Some browser OS combinations won’t work – we are steadily improving this, the custom installer is a new addition to the MyEclipse installer suite. I will admit that the initial progress bar isn’t great looking (it is only indicates the installation progress of a very small application), but it’s the best that is possible until the local installer runs, which certainly displays a very serious progress bar.
1) Can you send us a screenshot of the point at which it is stuck for you and what browser you are using?
2) The exact version of OS X, whether it is 32 or 64 bit and whether you have a 32 bit Java installed.
3) If you tell us what MyEclipse content you have under /Libraries & /Applications, I can tell you what to delete, if this is a working 7.5 installation, you don’t really need to delete it at all.
Sorry for the inconvenience caused.