another pack design you can do is:
http://www3.towerhobbies.com/cgi-bin...?&I=LXMUE5&P=7
Then you would just have to bend 4 battery bars to a 90* bend and one to join the two sides. I used this similar design for my crawler battery packs (3 on each side of the axle pumpkin). I also have 2 packs of that design for my gf's micro and I believe that is how they are wired..heh.
As for soldering the batteries pos to neg directly, the only way I have seen is with a "hammer head" tip and having the cells lined up and slide it down quickly so it sticks.
just found the vid on youtube:
http://www.youtube.com/watch?v=Ak2b7svVCYA