In your I2P configured web browser, you can use a Jump Service to jump to an I2P address that you don't have in your Address Book. Once you've jumped to the address, the address will be saved into your Address Book.
In an I2P configured browser, visit: http://stats.i2p/i2p/lookup.html (courtesy of Java I2P's lead developer zzz)
Then, you'll have two options:
For example, entering pinkpaste.i2p
into the Hostname lookup box (and then submitting) will return:
pinkpaste.i2p=m-HrPrIAsdxts0WM~P4mE8mt9P7g-QTaBvu7Gc6Nl0UX7Vwck-i~RvOPfK6W~kfdRvwhNTqevkBL2UF5l36We02Aiywu7kB2xOHRkze68h-Tg2ewvRVwokohguCD2G3wwAEz~7FVda2avYDCb9-N6TfuzxKLnmhPMvbNSjGL7ZsD2p-h207R3-2kvuMV9bfu-K~w9NI9XJhIyufvUnFYc2jnTVg8PbaR4UP57cNaOO2YIMPkbr6~yTcIu9B1sUfHK6-N~6virQDOxW4M-62rjnZkLpaCtkOsXslmCwZI--TkZ6hKi1kXZvNmJRE1rYfffYRFn38zhaqszeETX8HiIvahZhXF5fNumBziYdmLdw8hkuN1A~emU6Xz9g~a1Ixfsq1Qr~guYoOtaw-0rOFxNRS9yMehE-2LCb8c-cAg6z5OdlN4qJDl~ZHgru4d~EHp~BpAK3v7u2Gi-8l1ygVW-1CHVna~fwnbOPN3ANPwh6~~yUit0Cx1f54XiNRn6-nPBQAEAAcAAA==
Copy/paste this host=Base64 address pairing into your private Subscription.
For example, entering pinkpaste.i2p
into the Jump box (and then submitting) will automatically redirect you to the website and insert the Locally unique host into Address Book.