These have been taken from the White Dwarf that they were originally published and updated to fit in with current rules. Believe it or not these models only cost �3 each when they were first released.
Whirlwind and Tenderiser Rules
Cost- 150 Points per model
2 Whirwinds per army
2 Tenderisers per army
They can be fielded as a unit of two or four units of one
Each Unit takes up one special choice
Crew- 1 Boar Centaur
Boar Centaur Stats
M WS BS S T W A I Ld
7 4 3 4 4 2 2 1 9
Boar Centaur Rule
Boar Centaurs can take equipment at 2 times the basic cost.
1. The Whirlwind
When the Whirlwind charges into combat it causes D3 automatic strength 4 hits with its spikes and D6 automatic strength 5 hits with its rotating flails and scythes. The D6 score also indicated the number of ranks penetrated by the Whirlwind. This means that on a D6 roll of a 4 the Whirlwind would inflict 4 strength 5 hits with the flails and scythes and would potentially wound every model in the first 4 ranks. If the Whirlwind penetrates all of the enemy�s ranks, it passes completely through the enemy unit, and continues its movement measuring from the back of the rear most rank. If the remaining movement is insufficient to clear the enemy unit, place the model immediately behind it - the models move is extended further than normal.
2. The Tenderiser
When the Tenderiser charges a unit it causes D3 automatic strength 4 hits with its spikes and D6 automatic strength 6 hits with its concussive hammers. The D6 score also indicated the number of ranks penetrated by the Tenderiser. This means that on a D6 roll of a 4 the Tenderiser would inflict 4 strength 5 hits with the flails and scythes and would potentially wound every model in the first 4 ranks. If the Tenderiser penetrates all of the enemy�s ranks, it passes completely through the enemy unit, and continues its movement measuring from the back of the rear most rank. If the remaining movement is insufficient to clear the enemy unit, place the model immediately behind it - the models move is extended further than normal.
3. All Whirlwind and Tenderiser attacks are worked out first regardless of Initiative.
4. If a Whirlwind or Tenderiser is charged it may still attack as if it had charged but it causes only 1 automatic spike hit, and D3 flail/hammer hits. In this situation the weapon has been caught at a disadvantage and has consequently not gained sufficient momentum to fully activate its mechanism.
5. If a Whirlwind or Tenderiser penetrates right through a unit, the unit must take an immediate panic test, regardless of how many casualties have been sustained, on its own unmodified Leadership.
6. The Whirlwind and Tenderiser count as large targets.
7. The Whirlwind and Tenderiser count as light chariots and suffer the same terrain penalties.
8. The pavise in front of the Boar Centaur provides effective protection. It gives the boar centaur 4+ save after his normal armour save .The Boar Centaur has Heavy Armour and counts as barded.
9. To determine damage done to the Whirlwind and Tenderiser, roll 2D6 and +1 for every hit sustained and consult the special damage chart.
Special Damage Chart
3-7 No effect
8-9 The Boar Centaur is struck, taking 1 hit at the strength of its opponent or missile weapon.
10 The Boar Centaurs pavise is struck off and he no longer benefits from it�s 4+ save. If struck by a missile weapon of strength less than 5, the shot is not powerful enough to damage the pavise and the shot has no effect.
11 The machines steering is seriously damaged. On the D6 roll of a 1-3 the machine cannot turn right, or a 4-6 left, for the rest of the game.
12 The machine suffers damage to its wheels or axle, rendering it particularly unstable. The machine may move up to half rate (4 inches) without danger. If moving faster than half rate roll a D6: 1-2 nothing happens, 3-4 the machine moves forward D6 inches only, 5-6 the axle snaps and the machine comes to a complete stop. The Boar Centaur suffers no damage and may abandon the machine and fight individually.
13 The mechanism is damaged and the moving parts are jammed. The machine�s whirling blades or hammers are rendered inactive for the rest of the game.
14 One of the wheels comes off and the device immediately comes to a halt causing no further damage. The Boar Centaur suffers 1 strength 2 hit as he collides with the back of the machine. He does not get the 4+ save form the pavise. He may abandon the machine and fight individually.
15+ The machine is overturned, wrecking it and causing D3 strength 5 hits on the Boar Centaur and D3 strength 4 hits on any models in base contact.
Heres the original thread on HoH. Some of your questions might already be answered there: Whirlwind and Tenderiser Rules