How to inactivate Insert/Overwrite button?

How could I 'inactivate' the Insert/Overwrite button (located above 'Del' button)? I press it very often accidentally when I write something, and start to overwrite my text... I would like to keep the 'Insert' mode permanently.

I know that I succeeded to do it some times earlier, but cannot anymore remember how...

Can this be done with Allkeys? I already tried, but did not succeed... Can someone please give a template...?

@Gregor

I gave it a try with AllKeys, and it seems to work for me (tested with MultiEdit). Here's what I did:

Open AllKeys, then click the 'Add' button. When it opens the "Key learning window" press and release the 'Insert' key. There should be two entries in the window, one when the key was pressed, and one when it was released. Click the first one with the mouse, then click the 'Use Code' button. The key should show up in the main AllKeys window as "eat $80000047 RAWKEY Insert", with 'Translate into' blank. Select 'Use' or 'Save'. Voila! (Note that I have AllKeys configured to 'Eat all configured keys' and 'Flush upstroke of configured keys'.)

Of course, this will disable the Insert key for all programs, not just the one you're having trouble with- I don't know of any way to disable it only for specific programs.

To re-enable the key, open the AllKeys window, select the line for the Insert key, then click the 'Remove' button and then 'Save' or 'Use'.

Doesn't the Insert button act as a Help key? I'm sure it does here. Maybe I did something to activate that a long long time ago?

I think with "AT" type layouts, Scroll Lock is Help by default.