Green: Your archers
Blue: Your heavy infantry
Pink: You + Your Horse Archers
Red/Black: Your enemy
Stage 1:
Wait till the enemy charge has reached the estimated base (non pointy bit) of the arrow. Once they ride past that approximate area. Ride forth (with cavalry ordered to follow you) along the course as depicted by the pink arrows. When you arrive at the area with the pink circle. Stop your troop there and begin to hail the enemy charge with arrows, who at this point will have stopped at your infantry wall (blue) Continue to do this until the enemy sends in reinforcements. See Stage 2:
Stage 2:
Now the enemy as sent in reinforcements; Begin riding again with your horse archers along the depicted course, again depicted by the pink arrows. The red numbers represent the estimated position of the enemy army whilst the pink numbers show where your army should be at the same time.
The enemy (red/black) will follow YOU and your Horse Archers (pink) as the AI will automatically target the nearest hostile unit when they spawn in. When the enemy is in position 1, your group should be coming up behind your archer line (green). When the enemy is in position 2 you should be coming up behind your infantry line (blue) by the time you are in position 3, the enemy should have smashed into your infantry line (blue) whilst attempting to chase you. The enemy will change movement direction in order to charge directly at your group. This means you can easily "kyte" them straight into your infantry wall.
All you need do then is repeat stage 1 again. Then repeat as needed.
Noteworthy points; Your Horse Archers (pink)"might" hit a friendly troop inside the infantry line (blue) by accident however in my experience that happens only 2-3% of the time. A nearly stationary large blob of horse and rider is hard to miss.
You may find you can not manoeuvre fast enough and the enemy reinforcements hits your archer line instead. In this case you'll need to gage the size of the map and ride a little sooner. Sometimes you'll go too quickly and find the need to stop behind your infantry line and wait. You will get used to it after some trial and error. Expect very few casualties, even when up against double your numbers.
Rhod Sharpshooters are important because they will drop a significant group of the enemy cavalry whilst you and your horse archers are positioning at the enemies rear.
Remember: Do NOT instigate a charge with your infantry line, if you do the enemies reinforcements will likely cause you impossible problems as you won't be able to reposition.