Yes. It is available in the 6.2 version.
You are already there, just select the Page Action and then on the right side you will have an edit button otherwise double click to open.
By default it multiplies with 4x but there should be a way to change this formula in some files, otherwise it will be 2.5 - 10 seconds.
Lets wait, someone will provide the informaiton.
In the link you provided me it mention we can change the visit experience zone it will change the threshold of tolerating (as of my understanding). But i am not able to find that option under the general tab.
Visit Experience Zone is to modify the below thresholds, because in earlier versions this provision was not available.
You can check more about APDEX from the below link:
If I am not wrong the APDEX formula is already following the industry standards.
What I do not know to customize the performance baseline threshold for page load as you said 4 seconds (satisfied) to 10 seconds (tolerating).
Because the baseline configured time multiples 4 times for the tolerating actions.
Someone from the development will definitely share the way to customize. So stay tuned !!!
I found some really good following posts, so you read and find the experts comments about APDEX and User Experience Index.