First I'd like to say that I'm comming to the conclusion that Lilypond is a very good software for contenporary music. Not everything is out-of-the-box, but if you take your time I think you will not need to do hacks all the time like in Finale. I just finished a section of a ensemble piece, it looks great. I'm a new user and I hope I will no encouter very big problems on the road... :-)
I'm copying a part with a tablature and there is one measure that I have damped strings on the guitar. I'd like to notate this with a different notehead (a black square, or maybe a cross) instead and the usual numbers. Is it possible? The e-guitar have a non-standard scordatura, so I'm doing everything that is possible with tablature, since the players I'm working with said it is much easier to learn.
I modified a standard template to test this and it didn't work with the usual \override fot noteheads.