On the flash hit the mode button till you see M . then hit the S button so the 1/1 flashes then use the wheel to cut the flash duration down.
This assumes you are running your triggers so you have to it all manually.
The other option is to forego the triggers and take advantage of the built in wireless option so you can use PTTL.
You will have to set the camera flash to wireless mode and pop up the flash.
Then the 540 flash has to be set to wireless (middle power switch position). make sure the channels match.
Check the manual for exactly how you neesd to set everything.
Some people like manual everything, others like a bit of automation with the PTTL capabilities.
See this