Combining \markup and \override in a variable

[David Sumbler]

I have a bar which contains 3 notes, e.g.

fs4 ds as' |

It comes after a passage which is pizzicato, but the 2nd and 3rd notes
of this bar need to be arco.  However, a normal "arco" marking over the
d sharp does not make it sufficiently clear that that is what is
intended: particularly because of some earlier passages, a player might
easily think that the arco applies only to the 3rd note.

So I have a marking

larco = \markup { \larger \italic "┌ arco" }

The extra character is intended to make it clear that the 2nd note of
the bar has to be played arco.  In order to do that, the mark needs to
be moved to the left so that the little bracket clearly includes the
note, rather than pointing directly to it.

So that bar is now

fs4 \once \override TextScript.self-alignment-X = #-0.6 ds^\larco as' |

This works well.

My question is this: is there some way to include the position override
or a tweak within the definition of "larco", so that I don't have to
add it separately every time I use the marking?

I have tried a number of experiments with this, but so far I haven't
figured out how to get it to work.

David