I'm still trying to learn this stuff myself.  I couldn't find them in the WMI Object Browser, but using the "Scriptomatic" tool from Microsoft's scripting center I was able to browse through the root\CIMV2 namespace and come up with what looks like the right stuff.

Here's a portion of the script that Scriptomatic generated, which shows what kinds of things are available from the memory manager class.  There are lots of other classes with similar names.

For Each strComputer In arrComputers

   WScript.Echo

   WScript.Echo "=========================================="

   WScript.Echo "Computer: " & strComputer

   WScript.Echo "=========================================="

   Set objWMIService = GetObject("winmgmts:\\" & strComputer & "\root\CIMV2")

   Set colItems = objWMIService.ExecQuery("SELECT * FROM Win32_PerfFormattedData_MSSQLSERVER_SQLServerMemoryManager", "WQL", _

                                          wbemFlagReturnImmediately + wbemFlagForwardOnly)

   For Each objItem In colItems

      WScript.Echo "Caption: " & objItem.Caption

      WScript.Echo "ConnectionMemoryKB: " & objItem.ConnectionMemoryKB

      WScript.Echo "Description: " & objItem.Description

      WScript.Echo "Frequency_Object: " & objItem.Frequency_Object

      WScript.Echo "Frequency_PerfTime: " & objItem.Frequency_PerfTime

      WScript.Echo "Frequency_Sys100NS: " & objItem.Frequency_Sys100NS

      WScript.Echo "GrantedWorkspaceMemoryKB: " & objItem.GrantedWorkspaceMemoryKB

      WScript.Echo "LockBlocks: " & objItem.LockBlocks

      WScript.Echo "LockBlocksAllocated: " & objItem.LockBlocksAllocated

      WScript.Echo "LockMemoryKB: " & objItem.LockMemoryKB

      WScript.Echo "LockOwnerBlocks: " & objItem.LockOwnerBlocks

      WScript.Echo "LockOwnerBlocksAllocated: " & objItem.LockOwnerBlocksAllocated

      WScript.Echo "MaximumWorkspaceMemoryKB: " & objItem.MaximumWorkspaceMemoryKB

      WScript.Echo "MemoryGrantsOutstanding: " & objItem.MemoryGrantsOutstanding

      WScript.Echo "MemoryGrantsPending: " & objItem.MemoryGrantsPending

      WScript.Echo "Name: " & objItem.Name

      WScript.Echo "OptimizerMemoryKB: " & objItem.OptimizerMemoryKB

      WScript.Echo "SQLCacheMemoryKB: " & objItem.SQLCacheMemoryKB

      WScript.Echo "TargetServerMemoryKB: " & objItem.TargetServerMemoryKB

      WScript.Echo "Timestamp_Object: " & objItem.Timestamp_Object

      WScript.Echo "Timestamp_PerfTime: " & objItem.Timestamp_PerfTime

      WScript.Echo "Timestamp_Sys100NS: " & objItem.Timestamp_Sys100NS

      WScript.Echo "TotalServerMemoryKB: " & objItem.TotalServerMemoryKB

      WScript.Echo

   Next

Next

Hope this helps!