I've never used Mouse Raider (in fact, I tried to find it a year or two ago and came up empty, like you), but I think that AutoHotkey does much of the same thing. Coincidentally, I just used it for the first time yesterday to map actions to the right and middle mouse buttons in Warcraft: Orcs & Humans, since that game's archaic controls use only the left mouse button (unlike nearly every RTS that came after it). It works very well. Maybe it's not as simple as Mouse Raider, but it seems so powerful that it might be able to do everything that MR does and more.

Here's a link to the instructions for setting up AutoHotkey for Warcraft:

[url=https://pcgamingwiki.com/wiki/Warcraft:_Orcs_%26_Humans#AutoHotkey_script_for_better_mouse_controls]https://pcgamingwiki.com/wiki/Warcraft:_Orcs_%26_Humans#AutoHotkey_script_for_better_mouse_controls[/url]

That's a good starting point. You could tweak the provided script to work with Tomb Raider and dive into the AutoHotkey help file to figure out how to do whatever it is that you want to do.