Set Background Color hex Adobe Photoshop

Simple request, but I can’t find anything out there for help.
I have a user input added for a color background option in my script…
how do I tell Photoshop to set a hex color as the background color?
then to do a fill selection using mode multiply

thanks for any help.

This is just a guess. I don’t have the app but from perusing a photoshop scripting guide…

fill selection with contents {class:RGB hex color, hex value: "FFCC00"} blend mode multiply opacity 100 without preserving transparency

Perhaps something like this. Couldn’t say whether the hex value should be in quotes are not. If you have a variable, perhaps replacing the “FFCC00” (including quotes) would work.