Another Approach?
Hi I read that method and was planning to try it to root my Kindle Fire HD 7" (7.2.3.) as well. However, yesterday, I decided to try another method --it was mentioned in the Sparkym3 thread and mentioned /provided a link to a German page where they had rooted. That approach was (I think) different from the one you reference above, but it seemed straightforward and simple and when I used it, I was successful and fully rooted in about 40 minutes -and most of that was getting files and ensuring I had the instructions correct.
In case you want to try, here is that other approach (sorry if you've already read/seen this!).
1. I went to the (XDA) Kindle Fire HD 7" development thread posted by Sparkym3. It is titled: [ROOT][TOOL]Qemu automated root [09/18/2012] /showthread.php?t=1893838&page=14
2. I then went to Shadowmike's post, which is post nr. 131 (page 14?) and his post PROVIDES THE LINK TO "Root_with_Restore_by_Bin4ry_v17_dreamcodes.zip" batch file and part of the rooting routine for the latest rom.
3. So, for me, Bin4ry's "Root_with_Restore_by_Bin4ry" is the first part of the two parts that I used. The second part was QemuRoot_v1.0.zip (it is Sparkym3's original post nr 1)
[Oh, you may need to get a KF Driver to get the ADB commands to see the Kindle Fire HD. There are some in Sparkym3's original post, but I *think* I used adbdriver_v3.zip that I got from some other site."
4. Then, I just:
a. unzipped both files to C: (or near C: drive),
b. I connected my kindle, and ran the first file (root with restore). I let it do its full routine until done. (Ignoring the messages, except for when it would say wait or continue).
c. Next I ran the second file (QemuRoot) and let it run until it is done.(Still more messages, with bad news that I ignored

. I waited until that routine was done.
d. Finally I rebooted and I had root!
I was fully rooted and everything on the kindle still works (knock wood)
I have loaded Google play and all those Play store apps that I like from my phone (one point --I uninstalled and reinstalled youtube and ebay since they were FC after rooting. Now they are working well again).
Hope that helps.
Good Luck!