Here's a brief FIRST EVER BOARDING (in your game) method for Tits. I've chosen a Tit because they're less fragile than Rahanas, require less BA than Sanahars & they're relatively easy to find.. plus they can transport /any/ cargo in their huge cargo bay! It's a bit time consuming (10-20mins playtime) & the numbers may vary depending upon how many marines you have & what experience (level) they & your MO have, but it works for me:
Thanks to XenonSurf for his followup from my original post, I've decided to update this guide now v4.00 is out.  XenonSurf's link to much better boarding explanations here . [/edit] THIS IS STILL A WORK IN PROGRESS!
BR = Boarding Resistance; BA = Boarding Attack; cURV = Constructor URV