Why would you want to?
You may be able to if you have the right phone, but why would you want to?
The Beyond Talk plans have unlimited data and in all fairness to you, why not take advantage of this? You can't if you have a Talk/Text phone designed mostly for talking and texting and not designed as a true smart phone.
Three or four years ago when Virgin sold the Kyocera (pre-S2300) it was marketed differently. It looked like the 2300 and performed the same, but it was packaged and sold as a Beyond Talk phone at the time. I picked one up at K-Mart on closeout. Activated it on the old $25 Beyond Talk plan, and quickly learned that the very limited social networking app and basic email and horrid web browser just would not cut it, so I upgraded to the Optimus V, and then the Elite. Been a fan ever since. It simply was not an Android smart phone, just a basic Talk Text phone with rudimentary social and email and browsing interfaces built in.
If you truly want the Beyond Talk plan, I'd get a phone that takes advantage of the awesome data. If not, I'd stick with Pay-Lo plans since that's all you are really going to get with a Pay-Lo phone, and there are awesome Pay-Lo plans that offer real value for your dollar, IF talking texting and some basic other functions is all you want from your phone.
Whatever you decide, be glad you discovered Virgin Mobile. Both plans are awesome.