It will definitely fit and stay put better if bent to fit prior to assembly.
For parts like that, as well as ladders or railings I generally use super glue, but with metal-to-metal joints on parts that require more complicated assembly like radars and cranes I like to use an epoxy like JB weld because it allows plenty of wiggle-time and then dries very strong.
Edit: JB Weld is only good for non plastic surfaces. I attach the assembled PE parts to the plastic kit with either white glue or super glue.
_________________
The most attractive project, to me, is the one that I've just heard someone say can't be done.
