Full debugger support in BlackPearl for setting breakpoints and such is on its way.  In the meatime, save yourself some manual debugging hassle by emitting messages to the BP Console with this code:

string loggedInfoSource = string.Format("{0}/{1}", K2.ProcessInstance.Process.Name, K2.Event.Name);
K2.ProcessInstance.Logger.LogInfoMessage(loggedInfoSource , "Your helpful status message");

Note: You must run BPService in console mode to see these messages.  Be sure to run the BPService executable under priviledged credentials with "Run As ..."