This works for me when programmatically creating controls:
[myTextField.cell setWraps:NO];
[myTextField.cell setScrollable:YES];
Keep in mind that direct access to NSControl's cell has been discouraged since OS X 10.10 introduction:
Gradual deprecation of NSCell
Mac OS X 10.10 takes another step towards the eventual deprecation of
cells. Direct access to the cell of a control is discouraged, and
methods which allow it will be formally deprecated in a subsequent
release. A variety of cell-level APIs have been promoted to various
Control subclasses in order to provide cell-free access to important
functionality. NSLevelIndicator, NSTextField, NSSearchField, NSSlider,
and NSPathControl all have new properties for this purpose. Cell-based
NSTableViews are now deprecated, and view-based NSTableViews should be
used instead. Matrix-based NSBrowsers are also deprecated in favor of
the item-based interface.
https://developer.apple.com/library/mac/releasenotes/AppKit/RN-AppKit/