There are four areas to watch to establish/add long positions if we see continued USD weakness:
1) 1.04 should provide strong support if we see it, and will be where I start going long the pair. The level is previous resistance which has held multiple tests as support, and I am not expecting price to fall much below this level, if at all. The 100 , 55 , and 55 will be nearby, too (currently 1.0389, 1.0391, and 1.0381).
2) If we see sustained USD weakness and price falls below 1.04, the recent supporting will be the next area to watch, likely to be around the 1.0360/70 area.
3) While not likely to be tested, the last line of support for the pair is the main supporting that dates back to September of 2012. A daily close below there would be needed for me to close out my longs and take the loss.
4) Of course, there is always the possibility that we see big USD strength enter the markets, causing the pair to break through resistance at 1.0510. If this happens, I will go long on that break, when confirmed.