Well, it does take a while to make VX map like XP because of the way it handles autotiles but it's certainly possible, just more work. Bulletxt has a script that should allow you to change your tiles so you can have unlimited ones and KGC has one that will allow you to change the passabilities such as 4 direction etc.
As for the battle system, depending on how "customized" it is, there is a huge chance that you will need to rewrite the script to XP format because of the difference in structure. I believe VX uses the same format as Sephiroth's SDK (in XP).