Then you're free in your choice. HTML is quite flexible and you are not bound by typographical rules. I'd suggest not using quotes at all.
For short commands (say, up to 15 symbols) type them in-line, inside normal text, emphasizing with a monospaced font (or maybe bold monospaced or even color-highlighted monospaced) and being careful not to allow any line breaks inside commands (is it possible in HTML?).
As for longer commands, use the same font but write them on separate lines, and for very long ones — use several lines making line breaks in appropriate places.
And between command-lin-ery and surrounding text use vertical spaces of at least half the height of the font.