Downgrading radio - locked NVM directory

[bobsdesigns@hotmail.com]

In my efforts to get EVDO to work on my cricket based Touch, I found one step in an online faq which required modifications to a few files located in the nvm directory when browsing the phone using QPST or BitPim.
I have read that newer radio versions (3.x + with GPS) do an amazing job of locking these folders.
Would there be an issue with downgrading my radio temporarily to gain access to this directory, then upgrade it once again?
I haven't found anything which explicetly states this but I've seen a few hints that it may be an issue.
Please advise.

Alternatively is there another way into the NVM directory once locked?