Allow me to welcome you to the HP Forums! I would be glad to be of your assistance 🙂
I understand you are facing issues while setting up wireless on your Officejet 4630 printer since you cannot enter the "+" using the printer control panel. Ideally, there will be an icon at the bottom part of the printer touch screen which will give you all the special characters. Remember the old cell phones where you had to click on the "." to get the other special characters listed? Something similar.
If you still cannot get the "+" sign, I would suggest you install the printer using the USB cable and then convert the USB connected printer to Wireless to get it connected. In this way, you do not need to enter the password using the printer display.
To assist you with the specific steps I need to know the operating system on your PC. Please do let me know!
You can follow the steps mentioned below if you are using the Windows OS: