If you wish to use a variable instead of plain text inside the $readini identifier, you can.
For example if your ini layout was the following:
[section]
bob=hacking
And your script was this:
var %banslist = bob
var %test = $readini(filename.ini,section,%banslist)
Then the variable called %test will contain the word "hacking".
I hope thats what your after, if not then please explain exactly what your trying to do.