I am posting this here so that I can personally come back and refer to it later :)
Since I don't have a remote control for my Sony LDP-1450 (if they even make one), the only way to give it commands is through the serial port.
Using a term program such as "Tera Term Pro", one can easily issue seek and play commands to the player using regular ASCII.
To issue a search command to, for example, frame 12345: C12345@
To issue a play forward at 1X command: :
To play backward at 1X: J
To query current frame number: `
To start a REPEAT loop (2 iterations) from an arbitrary frame to dest frame 12345: D12345@2@
To pause the disc: O
To turn on index (ie frame overlay and more) : P
To clear all: V
To play forward at 1/5X : <
To still step forward: + (backward is , )