Rxvt-unicode && ISO-14755 input mode

On my FreeDSD laptops I use the rxvt-unicode terminal (version rxvt-unicode-9.31). This supports the ISO-14755 input mode: You long press Ctrl+Shift, type while holding them down the chars 2 6 2 d (without the spaces), and when you release Ctrl+Shift you get this glyph: . Or any other Unicode Codepoint you need.

I installed rxvt-unicode in my L5 and it starts, but I don’t know how to do the ISO-14755 input mode.