The best you can do is hope for a dodgy feed somewhere. It's a 3 o'clock Saturday kick-off, so officially, it will not be showing anywhere in the UK, but the games are all filmed, for broadcast abroad, and also for programmes like Quest's EFL (9pm Saturday).
If you scroll down a few days, there was a thread entitled 'Live streams for Millwall' on 12 Feb, and there are a number of links to live streaming sites in there - the last one being the best (for me, anyway). One of those will almost certainly be streaming this game. Note that there is usually a time delay, sometimes 3 or 4 minutes, and also that they never start broadcasting until the game actually kicks off.
Please be careful - if you don't have anti-viral software, these things will eat your computer alive. You have been warned. Apple Macs are safer to a certain extent, but no-one is safe these days.