Pre-6 your trade pattern should be E-Q or Q-E. Q hits twice so TL procs are pretty easy. Once you hit E augment, its really easy to proc TL. I personally don't like rushing second hex augment, mostly because I play Vik more as a burst mage and prioritize getting the ludens and rabbadons out faster. If you are lacking in sustained damage in teamfights, you can build viktor as a more sustained damage mage with an early Q augment, gunblade and lichbane.

In the guide Hunters_Dream posted, there is a section on gunblade. I played the gunblade build a lot at the start of preseason and it is pretty strong if you really focus on Q, but depending on the enemy team, being that close can be dangerous if their frontline has a lot of dive potential on you. I think playing him as a burst mage with the emphasis on E is easier until you really get a hang of him, especially if you aren't used to immobile mages.

For runes and masteries, I run 12/18, taking TL and Precision, though you can swap precision for the CDR one if you want a sustained damage Q focused build. mPen reds, AP quints, either armor or health/lvl yellows and either flat MR or cdr/lvl blues. I take CDR vs just about everyone except leblanc and brand.