Well I was a Guinea Pig for the last update since I was able to pull it the first day, I guess I could be one again.
Ann154 wrote:
Forcing the phone to 1x requires a different menu. The instructions are buried in the Thunderbolt forum in threads about the first MR1 update.
I know I'm the one who posted it back then lol
Update:
Dial ##778# and hit send
* A pop-up window named EPST will show up giving you 2 choices: View Mode and Edit Mode. Pick: Edit Mode.
* Enter the Password: 000000
* Go down to Modem Settings and pick “Rev A“
* You’ll want to choose enable and click OK, hit the menu button and then press “Commit Modifications.”
Your phone will then restart, once back on use LTE ONOff and select CDMA auto (PRL)
Then go into your setting and select software update then "Check new" and it should find the update.
I submitted this tip to droid-life.com and they used it on the website. I'm Aaron, which they mention at the bottom of the post 
http://www.droid-life.com/2011/05/13/htc-thunderbolt-users-experiencing-random-reboots-after-update/
Keep in mind the update has caused alot of problems for Thunderbolt users so make sure updating is really what you want to do.
After updating follow the steps above but instead of changing the modem settings to "Rev A" change it back to "eHRPD"(make sure to press menu and "commit modifications" when you change it) Phone will restart again.
Then using the LTEOnOff app change it back to "CDMA+LTE/EvDo auto"
---------------------------
It wasn't really changing to 1x it was changing the Rev A setting to enable instead of ehrpd. Then toggling from 4g to 3g is how it was able to pull mr1. this process isn't working anymore though, atleast with me.
Actually now that I look at the instructions Tboltaz posted, it was from the LTEpocalypse that most of us needed to force the phone to 1x. All in the name of getting some decent data speeds. 
lol
