I have recently done this on a Laguna key fob.
Yes its safe to solder to pcb, just dont use too high a heat if its adjustable, and use a fine point (i made one from a nail which i filed to a point).
I used superglue to keep it in place while i did the deed, but anything would do.
It may be easier to take a layer off the copper strip and solder to that, but be very gentle when doing that.
After youve soldered it, use some sort of ruberised glue on the connections to give them a bit of support (especially if you solder to the copper strip) as this will help to stop the joints cracking.
Main thing, take your time.
Good luck!