I’m using a 60% keyboard—the WASD VP3.

The built-in default mappings use Fn + ijkl as cursor keys.

Fn + i: up
Fn + k: down
Fn + j: left
Fn + l: right

But I prefer vim-like mappings:

Fn + k: up
Fn + j: down
Fn + h: left
Fn + l: right

Thankfully, the VP3 has 3 user-programmable layers—accessed by Fn + {<,>,?}. So I programmed the first of these layers to use the vim movement bindings. (I also then reprogrammed Fn + i to represent Home, which previously represented by Fn + h, would be lost in the new bindings otherwise.)

Steps

Here’s a link to the keyboard manuals and, as an example, the steps I followed to program Fn + j to represent the down cursor key instead of the original left cursor key. You should repeat these steps for each of the keys.

1. Optionally reset all your previous programming by pressing Right Alt + Left Alt. Wait until the left LED beneath the spacebar stops blinking.
2. Press Fn + < to select layer 1. The left LED lights up blue.
3. Press Fn + Right Ctrl to enter programming mode. The right LED lights up blue.
4. Press Fn + j (this is the combination we want to program).
5. Press Fn + k (this is the combination for the original down cursor key).
6. Press Pn to end programming of Fn + j.
7. Press Fn + Right Ctrl to exit programming mode. The right LED turns off.

To check whether the steps worked, switch to layer 1 (Fn + <), if you aren’t already in layer 1, then try to use Fn + j to navigate down.

I was unsure at the start of the process whether the VP3 keyboard would support programming combinations of keys (e.g. Fn + j), or if it would only support programming a single key (e.g. j). Luckily, it turned out that it supports the former.

Finally, by default, with switch 3 off the single Fn key in the bottom row is difficult to use together with hjkl. Turning on switch 3, located on the bottom side of the keyboard, converts Caps Lock to an additional Fn key. Less finger-twisting this way.

This way, I can comfortably use Caps Lock (now a Fn alias) + hjkl for cursor movement.