This is how I did it with my US spec HD-XA2.

Link to AVS Forum thread on A2 modifications

Link to AVS Forum thread on XA2 modifications

Here's how it went. I started with USA model XA2 with FW 2.8.

1. I downloaded US XA2 FW 1.3. (Link to US A2 and XA2 1.3 FW)
2. Modified the hex code as follows:

    Change hex value at row 3, column 7 and 8 from 05 14 to 0A F2

3. Saved the iso file as Moded 1.3
4. Burn iso file using Iso-Burner (Link to Free Iso-Burner)
5. Update the firmware on XA2

    The player will ask Update Firmware?
    Answered Yes, and player goes through Step 1 through 5. Display will say STEP X/5

6. Disc will eject and player shuts off.
7. Turn on the player.

    The player was set to 480i and I could not get into setup menu. (panic sets in)

6. I downloaded Modified XE1 FW 2.5.1 (Link to modified XE1 2.5.1 FW)
7. Modified the hex code as follows:

    Change hex value at row 1, column 12 to 16 from
    45 31 4B 54 59 to 41 32 4B 54 4E The ANSI should change automatically from HDXE1KTY to HDXA2KTN.

8. Save the ISO as modified XA2_2.5.1
9. Burn the modified ISO using Iso-Burner
10. Update the firmware on XA2

    The player display indicated VERUP - I pressed OK and hoped for the best.
    The player display showed Step 1 through 5. Display will say STEP X/5.

11. Player shut off and ejected the disc.
12. Turn on the player

    No display. Player's display window stated MSSG.
    Pressed OK on the remote.
    Display briefly showed VERUP and then started flashing 2 VERUP 1.
    Player shuts off.

13. Turn on player

    Still no picture, but the player is now set to 1080i.

14. Downloaded Official US FW 2.8.0.1 from Toshiba site. (Link to Official Toshiba FW Download page)
15. Burn the ISO using Iso-Burner.
16. Update the FW blind by loading the 2.8.0.1 CD.

    Player display showed VER UP - Pressed OK on the remote.
    Player display goes through STEP 1 through 5 and shuts off.

17. Crossed my fingers and turned on the player.

    Yay, display came back.
    The screen showed Version Updating. Press OK to continue.
    Pressed OK and display is once again gone.
    Player is flashing VER UP and then shuts off.

18. Crossed my fingers again and turned on the player.

    Everything comes back.
    Displayed briefly flashed Setting Resolution to 1080P24.
    Went into Setup and checked resolution settings

    up to 480P/576P is present along with other resolutions.
    The player FW is 2.8/T23T
    Display 1, 9, 5 Display command shows
    Machine Code: HDXE1KTY
    Submicom Version: HDA2TN1001TD
    Group ID: 0a
    Model ID: 88
    Package Version: 2801
    NAND Version: 6268
    NOR Version: 2801
    WinCE Version: 2801
    FWH Version: 1019
    Driver Version: T23T

So far, everything works. If I had to do it again, I would connect a monitor with composite or S-video out in addition to my HDMI just to see the menus and other display commands.

Now the tests.  First up was Region 5 PAL version of Night Watch.

    My Panasonic PT-AE2000U projector shows the display as 1080P50. The disc plays perfectly.

Next, Region 2 PAL version of City Hunter (HK Legends).

    My Panasonic PT-AE2000U projector shows the display as 1080P50. The disc plays perfectly.

Next, Region 3 NTSC Korean import of A Bittersweet Life.

    My Panasonic PT-AE2000U projector shows the display as 1080P24. Other than menu appearing somewhat pixelated (probably because the display is set to 1080P24), the movie played perfectly.

Next, Region 3 NTSC Korean import of Shadowless Sword.

    My Panasonic PT-AE2000U projector shows the display as 1080P24. Again the menu appears somewhat pixelated (probably because the display is set to 1080P24), but otherwise, the movie played perfectly.

Next, Region 1 Star Wars Episode 3 (RCE)

    A screen comes up stating, THIS DISC IS NOT FORMATTED TO PLAY IN THIS REGION.
    So I apply the RCE hack as follows:
    1. Open the tray, put the disk and leave tray open
    2. On the remote, do T.Search 1 3 9 <region number> T.Search
    3. Player should beep and "TEST" will be displayed on the LCD
    4. Press Play
    The disc plays perfectly. My projector also shows this to be 1080P24. This disc just looked fantastic, near HD quality on 1080P projector at 150" screen.

So everything works, including non-region 1 PAL, NTSC, and region 1 RCE discs. I am extremely satisfied. I am very impressed that this plays PAL discs at 1080P50 and NTSC discs at 1080P24. Thanks to all who helped on both AVS Forum and AV Forum.