1. Flash to stock MAKE SURE YOU FLASH THE PRE-XXXX STOCK FIRMWARE IN THE FIRMWARE PACK THAT IS EASY TO FIND. (read firmware from drive, then download the jungle flasher pack that includes all firmwares, load the correct stock firmware and inject your drives key\serial\etc).
2. Update your Xbox 360 to latest dash, this will update the stock firmware to the "POST xxxx" dashboard update.
3. Flash your drive with the relevent firmware using the "POST xxx" firmware and injecting your firmware key\serial\etc that you got from step 1.
This is covered in numerous places and I don't think you are "technically inclined" to be honest if you couldn't find this out for yourself.
note...
You may need some additional hardware depending on your drive etc.
Do a google, the info is all there.
ALTHOUH!!!
Don't do any of this until LT3.0 is out as you will only have to do it again and doing it now flashing LT2.0 will mean that you cannot play AP2.5 games without being flagged, so basically wait till LT3.0 then do the above. I've put "XXX" for the dashboard version because I've not got the inclination to check exactly which dashboard and onwards began flashing your drive to stock. The info is in the firmware pack thouh that is easily available.