Help "Flashing" HTC EVO 4G from Sprint to Boost

[musicfeind2001]

Now that I got a new phone for x-mas, my g/f is freaking out that she hates her boost phone. She still has her EVO 4G from our Sprint contract a few years back and is pushing for me to flash it to boost for her.
I'm not too bad with computers, but I don't know anything about these cell phones.
From what I'm reading about the process, I need a donor boost phone (my old Samsung Galaxy Prevail?) to take some numbers off of, and program them into the Evo? I see several lists of programs needed to do all this, and it just seems to much effort for one phone.
Do I really need to go through the process of restoring it to factory and rooting the phone, just to flash it? Everyone tells me I can just take it into a Boost mobile retailer and most of them are able to do it for a fee.
What do? I've read half of this walkthrough: http://androidforums.com/evo-4g-all-things-root/460035-evo-4g-boost-mobile-guide-evo-3d.html
Is this safe!?

 

[Rukbat]

Take it into a retailer who does it and see what the fee is. Compare that to the amount of time and work involved. Only you can decide which works better for you.

 

[ocnbrze]

it is safe provided you follow directions.....though messing with those numbers can brick it, so make sure you follow what the guide says.

now i have no idea on boost doing this or not for free.

 

[tube517]

I would just get another phone vs flashing it to Boost. It's not worth all the time and trouble anymore now that Boost has 4G/LTE phones. If you flash the EVO to Boost, you cannot get 4G. You could probably get a used EVO Design for Boost at the same price as you would pay to flash the EVO to Boost.