Hi, David. Standard Windows method for controlling this type of keyboard shortcut is to place an ampersand (&) before the selected letter. For example, if you have a context "@test" and you want the "s" to be the keyboard shortcut for this context, you could code it as "@te&st". When the context selection popup appears, you will see "@test" (notice that the s is underlined) and typing an s will select this context.
Drawbacks:
1. If you should happen to code two different contexts with the same shortcut MLO will not warn you but one of them will not work.
2. The only place where this keyboard shortcut is operative is the pop-up list that you get from right clicking the context field in a task list. Anywhere else, the ampersand will be visible. For example, if you select this context and the popup list is dismissed, your task list will now show context @te&st as opposed to @test or @test. If it is going to be a problem for you to see @te&st as the context then you should not use this function.