On 27 Dec 2014, at 20:25, Ross Ahmed wrote:

The R bundle includes the following command:

R > Execute Selection/Document In R and > Show Result as Tooltip

How can I get this command to work in .Rnw files?

You mean just enable the key equivalent for .Rnw files?

If so, add the top-level scope of a .Rnw file to the scope selector of the command.

The tooltips disappear after a few seconds—is there anyway of showing/hiding the tooltips with a keyboard shortcut?

No, once the tool tip closes the command has to be re-run to show it again.