I do not believe there is a way to "touch" the <tr> -- at least -inside- PROC REPORT syntax. That's because the <tr> tag is generated by the beginning of the row of data being sent to ODS. And, since the beginning of the row event in ODS -only- generates the <tr> tag, there are no hooks to that event inside PROC REPORT.
You can probably modify or create your own HTML tagset using PROC TEMPLATE for tagset templates, in order to put extra text into the <tr> -- because it is the TAGSET template that handles the row event. And, also, if you want to create a counter to put into the rows, then you'd need to get into the details of TAGSET template and event processing.
If you do not have experience with Proc Template for TAGSET templates, you may with to contact Tech Support for more help with this question.