You can use a small script -- you can assign any shortcut key to scripts in the Keyboard Shortcut Editor. Geek as I am, I wondered if it would be useful to make the script intelligent enough to not have you edit it for each diffrent character ... And Kris from Rorohiko wrote exactly that! https://www.rorohiko.com/wordpress/manuals/unicodeinjector-easily-insert-any-unicode-chara cter-into-indesign/
(All you need then is the Unicode for a long s. Finding that fhould not be a problem.)
If you are using OSX this simple script could have a key command assigned:
tell application "Adobe InDesign CC 2014"
--set the current text selection or insertion point to unicode 017F
set contents of selection of active document to «data utxt017F» as Unicode text
If you always wanted your s to be long you could assign the s character to the script when the context is text, like this where my script's name is LongS.scpt:
The problem is that ſ only occurs at the beginning of or in the middle of words. The s at the end of words is always short. And when you write a double s it is done with a long ſ followed by a ſhort s.
So Find and Replace only works manually. I ſhould like to be able to enter ſ as I type. Do you think this is poſsible?
I am wondering if it might be a good idea to edit the font(s) with FontLab Studio, placing the ſ in a place like Option+Shift+S where I can eaſily type it in.
Suppose you were to include a marker character with it? You could then use F/C to replace the marker and s.
I ſhould like to be able to enter ſ as I type. Do you think this is poſsible?
The key command attached to the script could be anything. Doesn't have to be the s in my example, could be Control-S etc.