This can be done in the hierarchy editor. Create a config view (File->New->CellView and pick your lib cell view and set the Type to be "config". Then when this opens, hit Use Template and pick "spectre". Make sure that the top cellView is pointing to your schematic and OK that form.
You'll then get a Table view showing Cell Bindings and a Tree View showing instance bindings - this is how you control which views are used for each cell or instance with greater control than just a view list and stop list which is applied everywhere.
For Ultrasim usage, use View->Properties. You'll see some additional columns appear in the table and tree view, including sim_mode and speed. You can click on these for a particular cell, or a particular instance. sim_mode is a cyclic with the various sim_mod choices (e.g. s, a, ms, da, df, dx) - and you can also set the speed.
Save your setup, and then you can hit the Open button in the hierarchy editor to open the configured schematic, From here, launch ADE (you'll see ADE shows the config as being the view being simulated) and then if Ultrasim is the simulator, it will take this information and add it to the netlist so that Ultrasim knows the per-cell or per-instance mode and speed settings.
Hope that helps,