Is there a way to disable the Speed Launch function (reader_sl.exe) through the program? I can't find a clearly marked option.

I would prefer to do it this way rather than using regedit or selective startup if possible.

In short, I don't think so. However here's a very easy to way to manage all user startups without using either msconfig, selective startups, or regedit:

http://www.mlin.net/StartupCPL.shtml

And, since I disable that with the above tool, I know for certain it will do the job.