Crosswind gusts are a bit of a gray area in the rules. The Boeing FCTM even implies that crosswind limits are a guide only, and not a strict limitation. On the day, it is down to the commander to decide if a landing may go ahead, subject to the guidance limitations in his Operations Manual.
A gust is only a short duration peak of the wind. Therefore the vast majority of time is more at the stated wind. The stated wind is what guides you on whether you may complete the approach, the actual threshold wind just before landing is what guides you whether you may complete the landing. It is overwhelmingly likely that your landing will take place at times when the wind is not gusting. Therefore, you may assume the wind is 090/25 and rely significantly on your own judgement. The gust figure is to guide you, not in this case to set a limitation on landing.
But if you include the gust figure, I make that a mental calculation of 35 kts, so I would forget iPhone applications in this case and rely on your brain! The HWC comes to 20kts (gust figure). That's the trouble with computers- rubbish in, rubbish out!
So, just use standard wind, and bear in mind gust factor, but don't let it spoil your day. And you have to have these figures mentally:
Wind/Track angle/Crosswind Factor/Headwind Factor
15............25%/97%
30............50%/87%
45............70%/70%
60............87%/50%
75............97%/25%
Learn it so you can reproduce it with one engine out, stewardess passing you coffee over your shoulder and copying Volmet at the same time!