urxvt is my favorite terminal emulator, but one thing I've always missed is the lack of some profile/theme selector functionality, so I created this Perl extension that implements this using dynamic colors and good old X resources :)

Perl is not needed.

URxvt.keysym.M-C-minus: command:\033]4;0;#333333\007\033]4;1;#cd3333\007\033]4;2;#33cd33\007\033]4;3;#cdcd33\007\033]4;4;#3333cd\007\033]4;5;#cd33cd\007\033]4;6;#33cdcd\007\033]4;7;#cdcdcd\007\033]4;8;#656565\007\033]4;9;#ff6565\007\033]4;10;#65ff65\007\033]4;11;#ffff65\007\033]4;12;#6565ff\007\033]4;13;#ff65ff\007\033]4;14;#65ffff\007\033]4;15;#ffffff\007\033]11;#101010\007\033]12;white

Yeah, actually I first thought about writing a script to translates normal X resources color schemes into urxvt keybinding commands with escape sequences like yours, but then while I was reading the documentation I discovered that urxvt has support for pop-up menus, so I created this Perl extension instead.

In case you need something more generic: https://github.com/dylanaraps/pywal

Does it support direct RGB colors (true color)?

To be honest I'm not sure, does vanilla urxvt supports direct colors?

Not completely, but there are patches and forks for this.