As you say, the root of your problem is not the trackpoint but to avoid frequent arm movements when switching between keyboard and mouse. For that, you may want to use the ThinkPad's touchpad with your thumb.
In contrast to using it with your index finger, there is no need to reposition your hand for switching between keyboard and pointing device. It took me 2 weeks to get used to it though. If you also want to avoid repositioning the hand for scrolling ("mouse wheel" use), there are at least two options:
- Switch to edge scrolling settings on the touchpad, so you can scroll with the thumb.
- Configure the trackpoint to do scrolling when having the middle button pressed. This works on both Linux and on Windows. On Windows, it is in the mouse options' "UltraNav" tab after installing the Lenovo UltraNav driver.
Before trying the "thumb on touchpad" option, I also permanently used the trackpoint. I had it on high sensitivity, but even then it would not do big movements fast enough for my taste, leading to using "excessive force" and then to pain in my index finger's base joint after some weeks. That's when I switched to the touchpad for regular use.