PokerTracker

Is it possible to create stat BB/100 for each position?

Thanks in advance.

You can see that in the Positions tab.
You can add any stat you like - Tutorial: Configure Built-in Reports.

Sure, but I would like to do little comparing. I think that would be easiest done in report page. I dont think there is configure report -button on report sheet or is there some other way to achieve this without coding stat?

You can add the BB/100 statistic to the top report on the Positions tab and see your winrate value for each and every position side by side without any programming at all. How else would you want to compare that makes this method insufficient?

First, I would like to filter opponents with certain VPIP:s and enough hands in my database. And then compare my positional winnings vs averages of other regs and certain opponents to try to find my and their leaks.

You'll probably find it easiest to filter your custom report by position in that case (using simple filters), and untick 'filter on active player' so that you see all players' hands/stats from one position in one report.
To filter by VP$IP you can enter a custom filter like:
#VP$IP# > 30

Tutorial: Custom Reports and Statistics

If you want to see a stat for each position in a single line of a report you will need to build a custom stat for each position - see How To: Make a New Version of a Statistic.