How to add shortcuts with "double tab" behaviour like GG for Vertex slide

I am a fan of those double tab operation calls like GG for Vertex slide. I am looking for a way to add shortcuts that work like “GG” but i cant find it in the user Keymap. Loking for vertex slide only gives me the alternate shortcut shift-V. No GG.
How can i add some? For example: Hitting “B” one time gives borderselect and hitting “B” 2 times gives circle select?

You can’t via keymap. The GG is specific to the Translate operator - move tool - (i.e. the second G is a modal key supported by that specific operator). It’s not a generic type of key mapping that could be applied to anything.
However, as far as selection tools are concerned, with default keymap the W key cycles between box, circle, lasso and tweak tools. That, again, is not something generic though - there’s a pre-defined list of tools and the key is mapped to cycle through that list.

Ah Ok, good to know.