In the current version of ESF (without any mods/addons) it's not possible to transform more than once.
In the new version currently in developement (esf 1.3) it will be possible to go up to ssj3 (no ssj4, because they don't want to add GT or movie content).
And please don't ask when ESF 1.3 will be out, it'll be out when it's done
One minor correction - the entire ESF Team and Forum Staff have disallowed the link of EVM for the reasons listed. It's hardly polite to single out moderators for upholding the forum laws..
Add-ons are kept to their own personal forums simply because we cannot be experts on all of them, and have no direct control over their actions. The extra publicity is appreciated but these are independant agents to whom we owe no real obligation.
Now, as the question has been answered - twice - and the issue itself can be sticky, I'll be closing this one. Apologies to Jan Emmers, you won't be playing as SSJ3 just yet. Soon, hopefully.