Hear is the deal, you would no longer gain new lay on hands. So what you have is all you will ever have, however the HV does stack for how much damage you would heal.
Example: If you were a paladin 5/HV1 you would still have Lay on hands as a 5th level paladin and it would still take 2 uses of that ablilty to channel, but you would count as a 6th level paladin for how much effect the channel would have
Your times per day would not increase as it is part of a paladins lay on hands, which the class does not increase. So while the number of times you can use it will not go up you count HV levels as paladin levels for what effect it has
Paladin 5/HV 10 has a channel still limited by his 5th level LOH number of times per day but count as a 15th level paladin for how much it heals {8d6} but each use still uses up 2 of your lay on hands uses
I'm looking at making a Paladin / Holy Vindicator. The only thing I'm having issues trying to figure out is how Channel Positive Energy and Lay on Hands would change? Would the Paladin no longer get additional Lay on Hands but would scale for Channel Positive Energy? As well as determining how the Positive Energy / day would increase.
-Exitilus
You don't get additional lay on hands or channels, but the power of the channels increase as you level up for purposes of determining the DC and the number of D6's you would get.
To be clear, HV only improves the damage on Channel Energy, not LoH.
That is, a Pal 5/HV 10 with a 20 Cha would have 7 uses of LoH. He could Lay on Hands for 2d6 healing, or he can use 2 uses of LoH and Channel Energy for 8d6 healing.