Though this is possible, but you will need to change a lot of things. Also, with any osclass updates you will need to do all that over again.
I suppose you want this for security reasons? Osclass out of the box is quite secure, and if you're really concerned about this page, go with sucuri and they have an option to add extra security passes for such pages.
Finally, if you have a new website, this should not affect at all. I've seen fairly big osclass websites having no security trouble with the standard admin url.