Replication With Updatable Subscriptions

I have been trying to set up replication with updateable subscriptions. I first followed the tutorial on MSDN and set up basic transactional replication. This all worked fine. I then tried, using that tutorial as a basis, to set up replication with updatable subscriptions.
On the Agent Security page you are asked for a Snapshot Agent, a Log Reader Agent and a Queue Reader Agent. I assigned these to the following accounts, which I created and added as logins, PUBLISHERSERVER
epl_snapshot, PUBLISHERSERVER
epl_logreader and PUBLISHERSERVER
epl_queuereader.


I then tried to set up a subscriber on SUBSCRIBERSERVER. Under the publication I add new subscriber, select the publisher, add SUBSCRIBERSERVER as the new SQL server Subscriber. In the Distribution Agent Security page of the wizard it asks for process account, which will be run when synchronizing the subscription. I entered PUBLISHERSERVER
epl_distribution here and selected the other two default options of connecting to the distributor and subscriber by impersonating the process account. I then took the default options for the next few screens and finally get to:

Login for updateable subscriptions. This offers the option of a login or using a linked server. I have tried various logins here, initially trying the €˜sa€™ login and password. This produced the error: The user is not associated with a trusted SQL Server connection. The servers are set up for mixed mode operation. I then tried PUBLISHERSERVER
epl_distribution and subsequently every other account I had created on PUBLISHERSERVER. All of these failed. I tried linking the servers, but this also failed. How exactly do you set up subscriber with the ability to login to the publisher? I have spent days trying to set this up, and am as you can gather new to this technology, any help would be greatly appreciated.