Sublimator's multiselect plugin (I've never used it) actually seems to do something similar:
From the docs:
You could use this in a hackish sort of way to create multiple insertion points: select the character to the right of each insertion point you want, and then when you've got 'em all leave this mode, press the left arrow key, and you're good to go. You could also edit the plugin or map these actions do different keystrokes (i.e. ctrl+i: "move characters 1 extend" to add an insertion point, then some key that leaves autoselect mode and also does "move characters -1").