Nope,
tried it, doesn't work as well as one would think it would ;o).
(It mainly has to deal with the fact that this would better be handled in kernel for more accurate timings to begin with (something that lab126 has actually tried, but has never been used in production, which should tell you something
); but mostly because of the latency involved in toggling the frontlight, which is subpar at best for this sort of usage).