As you can read at the winehq website, several stepsICQ5 thread @winehq.org are necessary:
-which patches: the one mentioned in Bug at winehq showing how to hack IE6 registry. It just comes down to removing this line from dlls/shell32/shell32_main.c (line 868):
SetWindowPos(data->hWnd,HWND_TOP,0,0,0,0,SWP_SHOWWINDOW|SWP_NOMOVE|SWP_NOSIZE);
-how to install those patches: just remove that line and recompile wine.
-which windows version(98,2k,xp) : 2k, but others work too i guess
-what wine settings: just default (only used win98 to install icq)
-which Dll overrides(really only shell32 and urlmon?): i did a bit of testing and basically you really need : urlmon, riched20 and msxml3, msxml3r.dll. Do not use native shell32, but use the hack above to get around the bug in shell32.
-whether you had installed some additional programs(like IE6 with ies4linux): Nope. Only thing i did is create the ie6 registry, to be able to install icq (see below), and install wine-gecko engine by command: 'wine iexplore winehq.org'
-Quick way to make it look like iE6 is installed:
notepad
wineserver -k
cat >> $HOME/.wine/system.reg <<"EOF"
[Software\Microsoft\Internet Explorer]
"Version"="6.0.2900.2180"
EOF
cxover doesn´t IE6 hack i guess..