dataset dtTr={...};
// A loose dataset containing new column order - each value
// represents column number in the actual worksheet,
// for instance {3,5,1,4,2}, that is the third column
// should be moved to the first position, etc.
loop(ii,1,dtTr.GetSize()){
  colmove r:=col($(dtTr[ii])) o:=last;
//Worksheet to reorder is assumed active, if not you should modify
// the "rng" parameter (r:=...)
  loop(jj,ii+1,dtTr.GetSize()) {
    if (dtTr[jj]>dtTr[ii]) dtTr[jj]-=1;
// modifying the "new order" dataset
// taking into account the changes after column moving
  }
}

range wks = [Book1]Sheet1;
int swaptimes = wks.ncols / 2;
loop(ii,1,swaptimes)
{
	int endcol = wks.ncols + 1 - ii;
	colswap rng:= [Book1]Sheet1!($(endcol),$(ii));
}