there is currently no way to do this, BUT i've often wondered if such a function wouldnt' be useful myself, and i have a good easy solution, which i will add in the new version to be released this month.
right now you only have 2 choices of what to show when the window comes up, either blank results, or last launched programs, in order of last launch.
what i propose is simply that you can specify what string to start out searching for when the window first displays, and in that string you could specify an alias group.
i know you might not be familiar with alias groups yet - hopefully my new demo movie will solve that, but suffice it to say that its very easy to make an alias group with exactly the programs you want in your startup list, in the order you want (and even with custom titles), and then simply tell F+R that you want the contents of this alias group to be show when the window appears.
sounds reasonable?