I’m not sure if I understand you fully. Can you please describe it more?
You want to add custom ID or class attribute to tooltip of eg. step 1?
From 2.1.0 of FREE version, there is already opportunity to target intro tooltip and highlighted layer per step by ID. Eg.
tooltip for step 1 id = dpintro-tooltip-step-1
tooltip for step 2 id = dpintro-tooltip-step-2
or highlighted layer:
highlighting layer of step 1 id = dpintro-highlight-step-1
so now you can use css
#dpintro-tooltip-step-1{
//your css code for tooltip of step 1
}
or if you want to target by step but also by tour (eg. tour with post id == 46)
.dpintro-wrapper-46 #dpintro-tooltip-step-1{
//your css code for tooltip of step 1 in tour with post id == 46
}
It is not like you can add your custom, but perhaps it is working for you also.
Let me know.