Hello,
searching a calendar for RC I found a http://code.google.com/p/myroundcube/source/browse/trunk/plugins/#plugins%2F... [1]
Reading license (AGPL) shows that the code can be modified, perhaps there is someone willing to deal with this plugin?
Regards
[1] http://code.google.com/p/myroundcube/source/browse/trunk/plugins/#plugins%2F...