Contact the manufacturer of the regulator and ask if you can do this first and foremost.
Some regs can have the HP burst disc and some other internal pieces swapped out to make it accept the higher pressure. Other times nothing can be done.
If the regulator is engraved as a 3000 psi system then the recommendation from manufacturers often is do not change it. If you have to hand your tank over to a fill station tech at your field or somebody inspects a tank when you are filling it from the 4500 psi line it can cause a serious amount of confusion and raise safety concerns. Especially when they see a reg that says 3000 on it but the cylinder says 4500; that's often where the confusion and concern comes into play.
Only do what the manufacturer recommends. Don't just take it upon yourself to just do it.