NewUser,
Welcome to SS forum, its a shame that nobody has answered your question to date. There is no specific guide on how to use them, but the attached thread, gives some ideas on how much of a pain they are and how to counter them, which will give an idea, how to use them.
I adopt same strategy as in RTW with Hellenic factions, from the front they are lethal, but you will need to protect the flanks and rear, with other infantry. On the battlefield you need to take particular care, as they can be quickly out maneouvered, so you need to protect them.
In a city, you could not have a better units, put them in a gateway or a narrow street, and you have got yourself a roadblock, infact a medieval tank trap.
Here is a thread
http://www.twcenter.net/forums/showt...ighlight=Pikes