Yes, you can use a Tamiya connector. Some LiPos come with multi-leads which have deans, Tamiya etc already wired in. I have one of the Vapextech 7.4v 4000MAh LiPo batteries which comes in a 7.2v NiMH style pack with three connectors. Works well for me.
I wouldn't hesitate to cut a connector off a LiPo and solder/crimp a new connector on. I've done this a few times. If you do so, though, bear in mind the consequences of shorting out the battery. Make sure you're crimping/soldering well so the connector can't come off and allow a short. Also only bare one wire at a time to make it impossible to short out the battery while you're redoing the connector. With care it's easy and safe.