I will try this and let you know if it will work.If you mean pic one blinks on whilst pic 2 blinks off, then you could create a datachange script on the $Second value. Make a tag alternate within the script, then use the state of that to blink each pic.
I don't have time to test this just now, but if you can't get it to work let us know, and I may get a chance over the wknd to test.