tweaking output in 2.3.16

[J. Scott Amort]

Hi,

As a means of learning the 'inner' workings of lilypond, I've been
trying to reproduce the exact layout of some complex scores.  I've read
through the manual and in consultation with the Program Reference area,
I've been able to adjust the default layout quite well to suit my needs.
However, there are two areas that I can't seem to find a solution -
slurs and spanners (specifically, hairpins and trills).

Regarding the manual positioning of slurs, I have found the height-limit
property of the Slur object to be useful in extending the arc of the
slur (to avoid collisions with some elements), but, I can't seem to find
a way to adjust the positioning of the end points of the slur (i.e.
closer to, or further away from the notehead).  In the reference for
2.2.6, there is an attachment-offset property that seems to handle this
sort of adjustment, but it does not appear in the 2.3.16 reference.  Is
there are way to do this in 2.3.x?

Secondly, I would like to be able to tweak the length of spanner objects
(specifically the Hairpin and TrillSpanner).  I don't seem to see any
reference to a property that allows for this - is it possible?

Thanks for any help!

Best Regards,
Scott