You could consider using "respectable" before it, which means"

Regarded by society to be good, proper, or correct:

[Oxford Online Dictionary]

1. Worthy of respect: estimable, 2. Decent or correct in character or behavior.

[Merriam-Webster]

The word "workaholic" itself has connotations of being too much focused on work without taking care of other things such as family issues and its meaning is negative. By putting those adjectives like "respectable" or "estimable", you could achieve what you want.

I don't think adding "tireless" before it reduces the negative connotation and it might work in the opposite way.

You could consider using "respectable" before "workaholic", which means:

Regarded by society to be good, proper, or correct

[Oxford Online Dictionary]

(1) Worthy of respect: estimable, (2) Decent or correct in character or behavior.

[Merriam-Webster]

The word "workaholic" itself has a connotation of being too much focused on work without taking care of other things such as family issues and its meaning is negative. By putting those adjectives like "respectable" or "estimable", you could achieve what you want.

I don't think adding "tireless" before it reduces the negative connotation and it might work in the opposite way.