The config file for shortcuts is in /home/username/.fluxbox/keys
Username being the account your on.
So go:
vim /home/username/.fluxbox/keys
or replace vim with whatever editor you use.

A few shortcuts will be seen, lets learn how to make or modify our own!

you’ll need to know this:
Mod1 == Alt
Mod4 == Windows key
Control == Ctrl
Shift == Shift

So a short cut for “alt+f2″ would be “Mod1 F2″.
The reset are practically the same as you would expect.

Thats pretty much it!
Heres a link to an example of mine