Does this mean just 4 lightbulbs? Or 4 'sets' of track lights with perhaps 4bulbs per track light set? (ie 16 bulbs)
The answer can make a HUGE difference because most dimmers would not be able to handle 16 bulbs.
The reason is that at 120volts and 15 amps, the circuit can only handle 1440 watts.
Even though you would be well under the maximum wattage for the circuit with 16 60 watt bulbs, or 960 watts total, this would be MUCH more than most dimmer switches alone can handle.
Most off-the-shelf dimmers are rated for only 600watts (In reality, only 80 percent of that or 480 watts.) Running anything more than 8 60 watt bulbs on such a dimmer is asking for trouble.
In such a case you would have to upgrade the rating of the dimmer to at least a 1000watt rated dimmer to be within a 'safe' operation range.