Updated connector modules for various X-Cart 4.x versions can be downloaded at
https://drive.google.com/a/x-cart.com/folderview?id=0B6p7sehSZL8_akhxR0VwQ0dta2M&usp=dri ve_web
Right now 4.5.4 - 4.6.4 available. Connectors for 4.0.x-4.3.x in the above folder are old (do not support iFrame integration and tokenization yet) and going to be updated within next couple of months, too.
I'll keep you posted as soon as we release new updates here.