'Normal' is used rarely in the rules but clearly seems to refer to a melee attack as outlined in the PHB 'Combat' chapter that i'm not going to quote extensively here for reasons of brevity. A spell touch attack, class ability, SLA or Special Attack may reference the rules for attacks outlined in the PHB but they are not themselves 'normal' melee attacks.
Thanks to the text in Complete Arcane, you can actually make an argument for Weaponlike spells (especially those that summon a weapon that you then use normally with some extra proviso, like touch attacks or free trips) counting as 'normal' attacks (and if melee ranged weaponlike spells, 'normal melee attacks').
Lay on Hands is not a weaponlike spell. It is a standard action that involves a melee touch attack. Ergo, it is ineligible as the target for the Smite Evil class ability.
However, I would houserule this is effective simply because it's two class features on a weak class and allowing them to work together in this rare circumstance allows the 'holy beatdown' that we all secretly want paladins to be able to dish out. In this circumstance, i'd treat the Lay on Hands as an unarmed strike (Lay on FIST) and then apply Smite Evil normally to the Unarmed Strike. This is even balanced - a Touch Attack is vastly superior to an Unarmed Strike in terms of hitting the target.
If I wanted to create some content for a Paladin who wanted to pursue this path, perhaps going into an Undead-Smiting PrC later, i'd do it in feat form like this.
Justiciar of the Dead
Prerequisites: Smite Evil or Smite Chaos class ability
You dispense Justice not just to the living but also to the dead. When using Smite Evil or Smite Chaos ability to attack a foe with the [Undead] type, you may also activate your Lay on Hands class ability using the same action/attack, channeling as many points of positive energy as you would normally be able to channel as part of Lay on Hands to damage the target.
In addition, you add your Paladin level twice to damage when Smiting the Undead, instead of once.
Normal: You cannot activate both your Smite Evil ability and Lay on Hands ability using the same action, your Smite Evil ability only adds your Paladin level once to damage when Smiting the Dead.