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!