Comment 9 for bug 1186810

no - no way to do it within the plugin - the "Loader" controls what python interpreter to use before running the plugin.

BTW - for my plugins I've introduced a ./install.sh type script that the user adds a parameter to install it either rb2 (by default) or rb3

i.e.

./install.sh --> for RB2
./install.sh --rb3 --> for RB3

https://github.com/fossfreedom/coverart-browser/blob/release-0.9/install.sh

An alternative is Donagh's method where it tries to recognise what version of rhythmbox is installed before installing the correct version of the plugin

https://github.com/donaghhorgan/rhythmbox-plugin-installer

Hope this helps.