How to make slow fade-in text on sugarcube?

Hi guys,

I would like to know how to make text fade-in slower than the default fade-in on sugarcube. I already can time the initial moment of the fade-in but the fade-in on itself is too fast. I would like it slow for dramatic purposes!

Here is a sample of the code:

Yada-yada-yada!<<timed 2s t8n>> Yada?<</timed>>

Thanks in advance!