You can do it using the Function node and a cull pattern node. You use the function to determine whether or not the values are equal, then use the resulting boolean to set up a cull pattern that will leave the desired input value, but remove the one you don't want.
I have uploaded a file called If_Then that demonstrates this.
I'm not sure I properly understood your meaning, but I gave it a shot. The file below will allow you to select from among a list of points with a slider. It then uses a similar set of Function nodes and Cull Pattern nodes to pass the selected point to one place, and the remaining points to another.