How do you select an ILS frequency when you can't see?
Depends on your familiarity of the actual aircraft that you are in.
If you know the frequency that the (presumably Nav 1 [for A/P coupling]) box is currently selected to - possibly aided by selecting ident on the audio panel (by touch - count the buttons from the left) and by having *LEARNED* morse code and being able to read it - you could then count the clicks of the frequency selector knobs and change from current to desired frequency and re-ident.
Fortunately the ILS does not require the CDI (or similar) to be aligned with desired - so I guess that the A/P should be able to cope.
I *have* personally tried the first part - ident and retune, whilst simulated "blind" - but I've never tried to couple an A/P aftwerwards.
The first thought that springs to mind is that many A/P's follow the heading bug - and you wouldn't be able to set that.....ahh, yes you would (with ATC and radar help).