Please advise when there's a method which works on linux.
OK, I've updated the procedure to work on Linux as well. Please see the revised item #1 under "things you're going to need". If you do it and it works, please let me know and I'll update the OP.
I took the time to edit the tutorial to reflect the
exact steps I used in Linux (Ubuntu 10.10). Here they are. (Should I post this somewhere else? Apologies if this is the wrong place.)
Detailed Procedure:
Attach your phone to your computer.
Unzip the SBF file that you downloaded in Step 4 of "things you're going to need" above. This will produce the file MC1_A855_1282081087_Recovery-Only_SPRecovery_0.99.3b.sbf.
Do not unzip the MotoCache1_Complete_Root_v1.1-update.zip file that you downloaded in Step 5 of "things you're going to need". You need to copy this file to the root of your phone's SD card and then rename it to update.zip.
Power down your phone normally.
Once the phone is off, slide open the keyboard and press on the "up" direction of the directional keypad rocker (the direction toward the screen -- which could really be to the right depending on how you're holding the phone) [pic]. While holding the dpad in the up direction, simultaneously press and hold the power button of the phone. When you see the backlight of the screen come on you can release the power button and the bootloader screen should appear (it will say "Bootloader" in the upper left corner). You can release the dpad. At the bottom of the text on the screen it should say "Transfer Mode: USB" if your cable is properly connected.
Open a terminal and enter the following text, but do NOT press the enter key yet.
sudo ./sbf_flash MC1_A855_1282081087_Recovery-Only_SPRecovery_0.99.3b.sbf
OK, this step is where you are going to press the "enter" key in the terminal, but don't do that yet. Before you press enter, read the next step. The next step (known as Step 10 in the original tutorial) has some timing sensitive tasks. If your phone has functioning FRS (discussed earlier), and you do step 10 wrong, you will have to start back over with this step as the FRS will undo the flash you just did with RSD. Once you've read Step 10 and know what you'll be doing next, go ahead and press the enter key to issue the command:
sudo ./sbf_flash MC1_A855_1282081087_Recovery-Only_SPRecovery_0.99.3b.sbf
After pressing enter, the flashing process goes through several distinct steps. This particular SBF file is very small so it finishes pretty quickly. Here's the output I saw:
$ sudo ./sbf_flash MC1_A855_1282081087_Recovery-Only_SPRecovery_0.99.3b.sbf
SBF FLASH 1.08 (mbm)
=== MC1_A855_1282081087_Recovery-Only_SPRecovery_0.99.3b.sbf ===
00: RDL03 0x80500000-0x80FFFFFF DEFE AP
01: CG47 0xC0A00000-0xC0DDDDFF 0FF0 AP
Droid found.
>> uploading RDL03
Uploading: 100% OK
>> verifying ramloader
-- OK
>> executing ramloader
Droid found.
>> sending erase
>> uploading CG47
Uploading: 100% OK
>> verifying CG47
-- OK
>> rebooting
It is said that if you don't "catch the boot" by holding up on the dpad key the OS will boot (and if you have functioning FRS the custom recovery you just flashed on will be put back to stock). I quickly held the dpad up key when I saw "rebooting" appear.
If you followed the instructions for Step 9 you have pre-read this step and knew to be ready for this. If not, your phone is probably already rebooted into the OS. If you failed to catch the boot, and the OS booted, let the phone finish booting, then power it off, hold the dpad up and power it back on. After that, continue through the steps like nothing happened. If your recovery got flashed back to stock we'll know it soon enough.
You should now be looking at the bootloader on the phone, and sbf_flash should still be saying "rebooting".
Power the phone off again. With the keyboard open, press and hold the "X" key on the physical keyboard and keep it held while you power the phone on. Once the phone comes on you can release the power button, but keep the "X" button held until you see the the Motorola logo.
When recovery starts, if you are presented with a screen with a gold colored android in the center that says "Patched by SirPsychoS (0.99.3b) on the second line of text (like this), you're in SPRecovery. If however you are presented with a screen with no text, and a graphic of a triangle with an exclamation point in it and an arrow pointing to a phone (looks like this), you're in stock recovery. If it's the latter, either you failed to catch the boot and your phone has functioning FRS (and it put your recovery back to stock) or something else odd happened (not likely). In any event, if you're in stock recovery you can't proceed so your only choice is to go back to Step 9 and try again. If you're in SPRecovery, congratulations -- move to the next step.
In the SPRecovery menu, use the volume up/down keys to highlight "install" and use the camera button to choose it.
Now highlight "Allow update.zip Installation" and choose it. [It will appear to do nothing -- that's normal. If you're unsure if you clicked it or not, choose it twice, it won't hurt.]
Finally, highlight "Install /sdcard/update.zip (deprecated)" and choose it.
The install should run to conclusion pretty quickly. When it's done it should look like this. If it does, congratulations, you're done. You're rooted with busybox, SPRecovery, and your FRS is now disabled so you won't revert back to stock recovery the next time you boot the OS. Enjoy!
I immediately did a "simple nandroid backup" before booting my phone into the OS.