You'll be able to edit in NTSC fine by using an NTSC project setting, but transcoding the video to MPEG2 for DVD authoring will prove a problem (potential sycnch problems etc).
I would suggest you look into purchasing software such as:
http://www.puremotion.com/dvconverter/index.htm
You can edit in NTSC, then export to DV AVI. Convert this to PAL, then transcode to MPEG. Although DV is a lossy codec, you should be good for upto 5 encodes before quality loss kicks in, so exporting and transcoding won't be an issue.