Apostrophes

I've always wondered, what happens when you write stuff like "'acciaccatura' has 4 'c's," how do you represent the plural of the letter 'c'. 'Cos when you write "c's", that's bad punctuation: apostrophes don't stand for plurality. But when you write "cs", it becomes ambiguous: just think of "as" or "is". How about "'c's"? That seems the most acceptable.

I remember reading Douglas Adams' "The Private Life of Genghis Khan" where Wowbagger the Infinitely Prolonged says "Right number of aitches, then?" while addressing the khan. There should be a standardised spelt-out form of each letter like aitch - for 'h' so that we can all happily avoid all that convoluted mess in the last paragraph.