It can be a huge can of worms if there is no provision for them. A gunsmith should be able to install a set for a few hundred dollars. You might be able to get a barrel band front sight and install a reciever sight of some sort. Otherwise if we are talking drilling and tapping your barrel and reciever you had better be equipped for precision metalwork or you might well ruin a perfectly good rifle.
I have a savage 64 gxp that I wanted to install iron sights on also.
I looked around but didn't find anything that looked very good, the barrel is tapered and not cut for a front sight so there weren't many options. The sights that I thought might work cost about as much as the rifle did.
I decided I would be better off buying a marlin 795 for $99 when they go on sale and having two guns than trying to add iron sights to my savage.
Yoshi, +1 on eadgbe194's advice. It doesn't make that much sense to pay for a gunsmith to make modifications to a cheap rimfire, because for the same amount of money or not much more, you can just get another gun. I ran into this situation with my Remington 512, which has notch sights. I wanted something so I could be more accurate for Appleseed. But it doesn't have tapped holes for scope mounts and aperture sights would be a similar problem. Plus, that's a nice rifle made in 1963, and it's also my first rifle to boot. It didn't make sense Bubba-izing it to turn it into something it's not.
So instead I just got a Marlin 795 for $110 after tax and rebate, put Tech sights on there (which go on in a minute, because the 795 is all set up for them), and now I'm good to go for Appleseed. And I still have the Remington 512 in its original configuration