It does not use spread directly. MT provides such parameter, but it is very unreliable.
The scripts use Ask - Bid whenever it is necessary.

Ahhh, I see.  Thank you, Popov...

Yes, you can in two ways:

1. export data with the desired spread: set the spread in points in the "Input" section of the panel, which appears when you drop a script over an MT chart. 0 mean automatic. Any number means the spread value in points.

2. you can customize the symbol settings in EA Studio.
Go to: Data -> Symbol settings. Then select the desired symbol. (You may load the data first)
Chose "Custom symbol settings" in the "Setting source" menu.
Set the spread in points.

See "Help" -> "Symbol settings" for more info.

Kind of related...

Where in the source code does a portfolio EA check for the current spread?  I've searched the source code for "spread" but it never appears.

1. export data with the desired spread: set the spread in points in the "Input" section of the panel, which appears when you drop a script over an MT chart. 0 mean automatic. Any number means the spread value in points.

2. you can customize the symbol settings in EA Studio.
Go to: Data -> Symbol settings. Then select the desired symbol. (You may load the data first)
Chose "Custom symbol settings" in the "Setting source" menu.
Set the spread in points.

See "Help" -> "Symbol settings" for more info.