I don't pretend to know a lot about it but I have had success in using both peroxide and Excel to treat algae on plants. It needs to be known that the type of algae that is treated is only the types that are hard to get rid of and not the common green spot or other soft algae.
The first technique is not really a dip but a simple straight application of Excel to the affected leaves. This kills both Black brush algae and staghorn in my experience and I have hear it will kill both hair and string algae. Simply use a syringe to squirt the Excel directly on the algae and in a couple days it will turn a brown/bronze color and die. Do not exceed the recommended dose for the tank size when you spot treat. It only takes a small squirt from the syringe to kill the algae and further treatements can be done daily to get the rest and keep it under control.
The second is the pyroxide dip. This one is tricky and should not be performed on delicate fine needle plants. You need a brand new unopened bottle of peroxide and you simply put the peroxyde in a bowl and dip the leaves, LEAVES ONLY, on the peroxide for 10-30 second. This will have the same effect of turning the algae brown/bronze and killing it. I do not recommend a pure solution if you have not read it will work for your plant. Some plants may react negatively to the treatment and could kill the leaves that were dipped. There are solution and concentrations that others have used but I used straight peroxide right out of the bottle on my Anubias Nana and it killed the algae but also damaged the older leaves which needed to be removed within a couple days. One last thing is to make sure you rinse the plant very well in fresh water so that you don't poison the fish when you put it back in.
The third option is and Excel dip. The concentration is 10:1 water:Excel. In this process, you can dip the leaves of most plants in the solution and it will kill the algae. The amount of time varies from 5-30 minutes but error on the low side until you see how your plants will react. I do not recommend putting the roots in the solution due to the possibility of damaging them. Experimenting with small amounts of the roots is a better choice so that if it does affect them negatively then you don't lose the whole plant.
NEVER dip the following in any of this:
Anacharis/Elodea, Vals, Criniums. Hopefully others will add tot he list and techniques for spot treating. Crypt may also suffer from Crypt Melt from any of these processes and I only recommend spot treating them in your tank. Warning: Any amount of peroxide in the tank will burn the gills of your fish and enough of it will kill your fish. Overdosing Excel will also kill your fish. Rinse all dipped plants well to remove excess amount of whatever used so that proper dosing will not be an overdose and endanger your fish.
But remember, this is to get rid of that which is is left over AFTER you find out where the imbalance is coming from and causing the outbreak in the first place. Balance is the main key to controlling algae and these are but small ways to get rid of it after you correct the cause.