You should have used ppcpimbackup from fdcsoft or spritebackup to backup your contacts in the first place, even microsoft Outlook could have worked
... however it may still be possible since you did copy the raw pim file. Complications as you are probably now aware of is that its a read-only file so you can't just copy the old one over to rewrite it. You can try using an advance file manager program like total commander, it allows you to copy/paste certain read-only/hidden/system files. If you manage to copy over the old file, do a soft reset afterwards so that your contacts refresh with the new information. Hope that helps.