To make a key act as the shift button,

q::shift

does not work, considering holding down q will repeatedly send q. With this set up, holding q will result in typing QQQQQQ.

This issue can be resolved by adding a keywait to q, and also by mapping shift q, as follows:

 q:: ;Shift   q
q::
Send, {Shift Down}
Keywait, q
Send, {Shift Up}
return

This works perfect for the q key, however. The numpad keys have the functionality where holding shift numpad acts as if numlock is off. From the ahk docs:

If NumLock is OFF but Shift is pressed, the system temporarily releases Shift and acts as though NumLock is ON.

So, if we use the same approach with numpad7 that we did with q, we end up sending Home repeatedly. I tried multiple ways to resolve this issue, but could not find a way around it. This was my simplest attempt:

numpad7::
Send, {Shift Down}
keywait, NumpadHome
Send, {Shift Up}
return

Does anyone have an idea on how I can achieve this functionality?