I want to get one but it looks like the cables running along the bottom of both my top and bottom tubes will prevent me from doing so. I was actually thinking about putting it on top of my top tube.

To those who have one, where are you putting it?

You generally have gravity working against instead of for you if you try to mount it on top the top tube. Generally bad idea.

My buddy has a Cannondale carbon bike and the only place he could mount his Minewt X2.dual battery was under his handlebar.

If it were me I would mount it on the helmet. Since I recently added a helmet light after having only a bar light, I would much rather have a helmet mounted light if I only had one light. I do all road riding in a group on rural, unlit roads. It is great to be able to see ahead into a turn.

You could put it in a Bento Box (http://www.trisports.com/benbakis.html) on the toptube. I've considered this myself.

Top of tube would be fine, just yank the strap tight and run the straps under the cables

you can use a rubber adhesive chainstay protector, glued to the top
tube for added anti-rotate support, but I don't need one, and I use a trinewt
on the top tube of my litespeed.

I've borrowed my wife's minewt, tried it on the top tube (tips over to the side but continues to work fine) and downtube (actually fits in pretty well at the top, propped up from below by water bottle). Use the 12" extension cord from niterider.