Custom data type in ModelSim

[XYZ]

Hi,

I created a custom data type in VHDL package

type my_type is ('A', '0', '1', 'B')

and conversion functions so that ModelSim uses my_type to represent data.
How can I modify line styles that ModelSim uses to plot timing diagrams?
Both 'A' and 'B' are red (the same as 'U' in std_logic) but I would like
'A' to be drawn as blue line with logic value 0 and 'B' to be blue at
0.5. Is it doable?

Thanks.