Lionel postwar, 151, seaphore, 154 highway signal and 153, block wiring question

This is the general method for using insulated track and will work for the 151.

For the 154, you could  do it the Marx way:

Or you could segment the ground rail of any straight or curved section of track by cutting with a Dremel wheel and reassembling the rail with fiber pins... the basics can be found here(Marx discussion, but works with the 154 too...):

Triggering Marx Signals

Here is a good close-up of the original Lionel contactor for reference(from Jeff Kane - The Train Tender):

For fixed voltage, the right post of the signal goes to the transformer instead of the "1" clip on the contactor.

And here is how I do it(the binding post on the right is connected to fixed voltage):

Also, check out this discussion on Realistic Flashing for a 154 Crossing to use the 154 with a regular insulated rail section.

For the 153, you may want to stick with the 153C contactor, a SPDT weight activated switch that switches the red bulb to green & back, until you know how you want to use it, then there are several ways to use insulated rail with relays and additional bulbs.

Hi Jerry - Maybe you'll find this helpful as well.  The book is called Wiring Handbook for Toy Trains, ISNB 978-0-89778-533-4.  Please see the attachment for chapter 14 for Train Activated Accessories.

Thank you very much for all your help, greatly appreciate it.

Best, Jerry