I covered setting the logging level for IMAP with the Exchange Management Shell a few weeks ago, but I keep coming up with more items to track. The expected syntax is below.
Set-EventLogLevel “MSExchange ActiveSync\Requests” -Level High
To find the available processes for logging (you put them between the quotes if spaces are present) enter Get-EventLogLevel in the Exchange Shell and you will be presented with an impressive list.
And again, the available levels are Lowest, Low, Medium, High and Expert.