Ok, I'm a hacker, let's see whether we can fix that!
The Yahoo Widget consists of a couple of HTML, image and JavaScript files, packed into a proprietary format. Finding out the URL queried by widget to retrieve the information was no problem and the returned data are in an easy to parse format. So the rest of the work was to assemble a Plasmoid which makes use of these 'webservice'. Two days later (had to buy some xmas presents in the meantime ;)) there is a working version available:
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Of course this Plasmoid is only useful for all KDE users living in Dresden (maybe 10? ;)) so I'll make the code available on my private website only, or provide it by KNewStuff later.
Update: You can find the sources and the compile instructions now under http://wgess16.dyndns.org/~tobias/kde/plasma_dvb/index.html