How to add an A with Taq

[Juan Pablo Labrador]

Does anyone have a reliable protocol to add terminal As to PCR products
produced Pfu polimerase or any other than Taq.
I think that it is possible to do this incubating the PCR product for 
some time at 72 degrees with Taq polimerase.
What I don't know is how much time should I incubate
if I have to add dATP and the final concentration
If I have to purify the PCR product before adding the As with the Taq 
or I can use the Pfu polimerase mix without any further treatment.

Thanks in advance for your comments.