Perhaps try local resources and active websites. Sometimes a large, vibrant community is better than mediocre standards.
Morse Codes for Computer Access
I have codes defined in two "groups" and use a code to switch between them. This enables me to reuse the same codes for different functions in different groups. A third code group contains codes that are always active, such as commands to switch between the other code groups.
Modifier keys (Shift, Control & Alt) release after the next code for a non-modifier key is sent. If a modifier key is needed to remain active for multiple keys then the hold/release code can be used to keep it active until the hold/release code is sent again.
To move the mouse pointer, send the code once for the direction (up/down/right/left) then the repeat code (a single sip). The mouse continues to move in that direction until either a single sip or puff will stop it. The standard mouse move is set to move 4 mickeys. When I need to be more precise I send the "mouse zoom" code which changes the mouse moves to 1 mickey.
A " · " is a sip and a " - " is a puff.
Alpha-Numeric Code Group
Mouse/Windows Code Group
The above website had links to other resources as well. The above seems to be an article "Morse Codes for Computer Access" in Assistive Technology and Electronic Aids for Daily Living.