Your question is a bit unclear. Are you trying to go from 1 to 10 then from 10 to 1 once (20 steps) or to go back and forth between 1 and 10 in 100 steps ?
If it's the first, you can try something like this:
for(var i:int = 0, j:int = 0; i < 20; i++){
if(i < 10) j++;
else j--;
trace(j);//put this in your text field
}
if it's the second:
for(var i:int = 0; j:int = 1, k:int = 0; i < 100; i++){
if(i % 10 == 0) j *= -1; //every 10 steps flip (multiply by -1) the increment direction(increase/decrease)
k += j;//increment k based on j which will either increase or decrease
trace(k);//use this value
}
However the textfield will update right away. If you want to display this change in time you can use the ENTER_FRAME event to increment (rather than the for loop) or a tween engine to animate the value