Like the link stan2004 supplied, to make it work you'll need a circuit board of some sort. There are a few companies that have made them in the past. Some of them are meant to flash LEDs though and may not be able to handle the current needed to light the bulbs the 154 uses. Lionel has one mounted to the bottom of their newer "154" signals, and I was able to buy a signal once that someone had converted with that board. I do not think Lionel sells the board anymore though. At least they weren't available about a year ago when I wanted to add it to another signal.
The signal originally came with a track clip called a 154c that provided the flashing circuit. It didn't flash the lights evenly though, as in one light may be on for 1 second and the other only for a 1/2 second.
I'm sorry I wasn't much help on this one; hopefully someone else will chime in with a company that makes the board you need.
J White