your problem sounds wired. For what reason do you want to switch the postion of only two elements in an array?
Nevertheless I guess indexing is the only way to switch the positon of two elements. Also you need a temporary variable to store one of the objects. My solution would look like:
X = [1 2 3 4 5]; temp = X(3); X(3) = X(4); X(4) =temp;
If you need more than one time write an function with X and i (element you want to switch) as input argument and x as outputargument.
Kind regrads, CN