Can you eat the seeds of Tamarind if you roast them or boil them?

They're certainly edible, but you might have to work for it.

A Western view from Purdue CropINDEX:

Tamarind seeds have been used in a limited way as emergency food. They are roasted, soaked to remove the seedcoat, then boiled or fried, or ground to a flour or starch. Roasted seeds are ground and used as a substitute for, or adulterant of, coffee.

People from more native cultures are perhaps more willing to put in the effort:

... But I was surprised to find those semi-charred seeds tasting wonderful. They were a little like well-roasted peanuts without their disadvantages, and gave me both the challenge and company I seek of suparis!

I also found a few other mentions of them being a snack food, something people had eaten at home, like this one, which also mentions roasting and de-shelling in bulk with a grinding stone.

As for how to prepare them, I think your best bet might be to roast them, peel with the aid of a mortar and pestle (to crack them open), then soak for overnight or for a day in buttermilk like this recipe suggests. It's worth looking at the full recipe - there's more detail and a little background.

You can certainly try them before soaking as well, if you're looking for something that takes work to eat - you might have to suck and chew a while. As the recipe SAJ14SAJ found says, and says "This is the real test for teeth as it is very hard and crunchy."

Yep, they are edible and I am eating them right now. They are roasted untill they turn black charcoal colored and then peeled. The kernel smells a bit like coffee bean. They are very hard to bite, so they must be kept in the mouth for some time mixing with saliva and eaten slowly.

It helps people who have a habit of constant nibbling, so they can engage their mouth and at the same time have a cholesterol free, slow to eat, healthy snack.

I have myself ate roasted tamarind seeds in my childhood. We eat that like candy (Top black cover has strong taste but core tastes similar to roasted peanuts but not same). Many people from Gujarat state of India call it 'kachika'.

According to Plant Cultures,

The seeds are also edible and flour made from them can be used to bake cakes and breads. Roasted seeds are reputed to be delicious.

Finding recipes that address removing the very tough seed coat is difficult, especially since there are false hits for the flesh or pulp of the fruit, as well as many non-culinary uses. Here is one set of instructions.

I just soak the seeds until the skin is soft. This takes a few days, and the water has to be changed every day. Afterwards, you can wash and roast or boil them as you like.

Some people are making a desserts with tamarind seeds... I just like to make tea with it...

I soak the tamarind in hot water or boil for a few minutes and drink as tea. I prefer it to tea and coffee but wasn't too sure what to do with the seeds. So I figured, if tamarind is edible, then the seeds should be too. I remove the skin, let the inside seed dry, salt it a bit and roast until it's golden brown. I keep them in bottles or plastic bags and, when it's cold, I snack on them and especially like it as a late night snack! It's yum!!!