In VMM 2008 R2 SP1 RC, here is the snapshot on how to set the Dynamic Memory.
On Memory -
You can configure Startup memory, Maximum memory and Memory Buffer.
To set memory weight/priority, click on Priority
The top is for CPU Priority and the bottom the where you set memory priority. Rather than sliding bar as what display in Windows Server 2008 R2 SP1 RC, in VMM it is using option. You can select High, Normal, Low or a custom value.
To View the value in VMM Administrator Console, you can add the column to view the similar display as Hyper V Manager snap in.