First you’ll need the following:

• A permission hacked S60 phone, follow my previous guide, hack S60 file permissions
• If you have a Symbian 9.2(feature pack 1) device, download installserver92 file.
• If you have a Symbian 9.1(pre feature pack 1) device, download installserver91 file.
• File browser eg. Y-browser, X-plore.

The list at the bottom of the post will help you decide which file you need to download.

Extract installserver.exe from the appropriate zip you have downloaded.
Copy it from your PC to your memory card, I put it into Memory Card/Apps
On your phone load up Y-browser and copy it from E:\Apps (If you are using the same location as me)
to C:\SYS\BIN

Remember you must have a permissions hacked phone otherwise you will not be able to see C:\SYS

That’s it, You can no install any Unsigned application without the need to selfsign each one, just install like normal and you will no longer receive certificate errors.

Here’s the list of devices to symbian version

Symbian 9.1 devices:

Nokia E61i
Nokia E65
Nokia N93i
Nokia E62
Nokia E50
Nokia N77
Nokia N93
Nokia N73
Nokia N80
Nokia N71
Nokia N92
Nokia E70
Nokia E60
Nokia E61
Nokia N91 8GB
Nokia 3250
Nokia 5500

Symbian 9.2 devices:

Nokia N82
Nokia E51
Nokia N81
Nokia E90 Communicator
Nokia N76
Nokia N95
Nokia N95-3 NAM
Nokia N95 8GB
Nokia N81 8GB
Nokia 5700 XpressMusic
Nokia 6110 Navigator
Nokia 6120 classic
Nokia 6121 classic
Nokia 6124 classic
Nokia 6290