I finally screwed up the courage to root and install cm7 on my milestone...and what a difference. Thanks to everybody on this somewhat dead thread.
I did run into a few stumbling blocks probably because I'm not familiar with the process and I thought I'd add my two cents to maybe help out...if anyone else every does this to a milestone and stumbles on this thread like I did. You will notice I repeat myself a lot...hopefully that saves confusion but may end up causing more.
Before you do anything, make sure you don't have an Open Recovery folder, or zip or update.zip on your sd card...if you do, delete them. This will save possible confusion later.
I downloaded right to my sd card and unpacked the andoiriani open recover right to the main sd card directory. That put an Open Recovery folder and a new update.zip onto my main sd card directory.
This is very important...and it took me some time to figure it out....you have to create a folder /updates in your new open recover folder. While youre downloading, if you do like I did, download whatever version of update.cm7.zip you want and google apps to the new update folder in the Open Recovery folder.
They must be in this new /updates folder otherwise you will not be given the option to choose them when you get into open recovery mode.
code.google.com/p/androidiani-openrecovery/
https://github.com/nadlabak/android/downloads (I used the 7.1.5 version, update-cm-7.1.5-Milestone-KANG-signed.zip) So far, working like a charm.
wiki.cyanogenmod.com/index.php?title=Latest_Version/Google_Apps
Once you have open recover unpacked and cm7 and gapps copied to the /updates folder in open recovery folder, then it's time to use RSD LITE, to root your phone.
Once rooted, then you will have the option of doing a nandroid backup once in open recovery mode. I chose to use Titanium backup, (downloaded from google market), for my backup tool.
Once you do the button dance to get into open recovery mode, (for me, it was camera+power to get the triangle, then volume up+power to get into open recovery mode), you will see a whole new menu, (the one in the first post), and you now have a bunch of things to do in there. Do them all or you may get the endless boot thing or some other problem. I got the boot loop until I went and did all the wipes.
Using the D pad, scroll down to the options, Wipe Dalvik Cache, Wipe Data/System Reset and Wipe Cache Partition. You select the option by carefully pushing the center of the D pad. I'm not sure if the order matters but I wiped the system first, then dalvik cache then wiped the cache partition.
The androidiani version of open recovery is slightly different that what is pictured...for one, it includes a baseband option...which you'll need later.
Once that's done, then you can install your version of cm7 and google apps. To do this, scroll down to apply update and select. The next page will give you the options of updating using the cm7.zip file you downloaded and the gapps.zip. If you don't have these options, then you didn't put them in the /updates folder you created in the open recovery folder on your sd card.
Select them one at a time...and before you reboot...here's where you scroll to the basebands option and choose your region. It is important...that's how your phone learns your mobile company.
Choose the reboot option and you should be booting into your new cm7 milestone...and mine came ready overclocked...and underclocked right out of the box...you have the option of changing those and so many more settings to your hearts content.
I don't know if I added anything or just made it more confusing...I thought it may be helpful to some to know what roadblocks I ran into.
Totally worth it and once I worked out how, way easier than I expected.
Thanks to everyone.