I think this should already be possible by following this property name scheme:
rapidminer.<your_plugin_name>.<first_subgroup>.<next_subgroup>. ... .<parameter_name>
For example, you could invoke the following method
RapidMiner.registerRapidMinerProperty(new ParameterTypeBoolean("rapidminer.my_plugin.my_property", "Tooltip for your property", true));
in a static block of a class which is definitely loaded during plugin loading. I did not test it but it probably works.