You can load 4D volumes as either multivolume nodes or volume sequence nodes - you can set how it is loaded by default in application settings / DICOM section. You can also choose how a particular sequence is loaded if you open Advanced section in DICOM browser and click Examine then select one from the listed loadables.
Probably volume sequence is somewhat more convenient to use, as it automatically separates out a volume. You can choose which one, by using the play/pause/prev/next buttons that appear on the toolbar. You can do further processing, such as create a 4D segmentation sequence (I can give you more instructions, if needed), compute displacement fields (to propagate segmentation from one frame to all the others fully automatically; or compute landmark point positions defined in one frame in all the other frames) by using Segment registration module.
Multi-volumes have some nice time series plotting capabilities and you can enable separating out a single frame by using Multi-volume explorer module.