Yeah, if you have a PS3, it'll be easy as pie to get it activated.
1) Connect your Vita to the PC using QCMA and a USB cable connection.
2) As soon as you are successfully connected, disconnect, but don't click off of the error message yet!!
3) Place the USB cable (still attached to the Vita) into the PS3, and when the content management appears on the PS3, click off of the error message on the Vita.
4) On your Vita, now set up a USB connection to the PS3 like you usually would. It should now bypass the update nag.
5) Transfer something from your PS3 to your Vita to automatically activate it.*
*your PS3 and Vita must be linked with the same PSN account to do this.
Hope this worked for you.