As vsjones answered, you can use git-svn to checkout a Subversion repository, use it as a local Git repository, and then post back up to it. You can even use the Microsoft Git Source Control Provider to allow you to integrate Git with VisualStudio.
HOWEVER, I would like to ask you why you want to do this. It appears that you could be what we in CM parlance call Crawling into Your Cave.
Crawling into Your Cave means that instead of working with everyone else, you're going to do your work in private without any oversight. You want to get your code to be absolutely perfect. You want a masterpiece of computer code. Then, you're going to unveil it to the unsuspecting world that will be wowed by your coding skills. You'll be hailed a genius and maybe even get a chance to talk to a girl.
Of course, the problem is that coding always works out best when it is in public view. Code reviews aren't just for completed code. It's also for code while it is being written. Before you go too far down a blind trail.
Another issue is a tendency for developers to bite off more than they can chew. If I need to check in my work on the same trunk as everyone else, I am more likely to take smaller bites of code. (Yes I could have made a pun on bytes, but I'm trying to be serious). I'll make a change, maybe add a few methods, test and commit. Then, do more changes, test and commit.
I use to be a ClearCase administrator. In ClearCase, each developer gets their own development stream. You code on your stream, then merge your work into the integration stream. (Basically, everyone got their own branch, and you merged your changes into trunk). As part of my job, I would hassle developers to check in their changes. I ran reports looking at the last time a developer delivered code. I constantly had to handle merge issues. I felt like a cop on a beat.
Then, I had a job where everyone used CVS. In CVS, branching is a pain, so everyone worked on the same branch. I couldn't imagine how this would work. How can three dozen developers work all on the same branch? Yet, over time, I started to realize that not only could everyone work on the same branch, but there were fewer problems. I no longer was the beat cop, and instead of making sure all the developers followed the rules, I could do other CM functions that I never had time to do. My relationship with the developers changed. I was no longer the guy who came around and told them what to do. Instead, I was someone who could help.
So, be careful about doing your work in your own private repository and then delivering the finished product to your team. If you are doing major work that will require long term development that might break the build while you're doing it, ask for your own feature branch in Subversion. That way, everyone will see what you're up to.
This isn't to say there isn't a legitimate reason for using git svn. I personally like checking in my code every few minutes. This gives me the ability to revert a file as it was five or ten minutes before I started making a mess. I still take small bites, and I check in my code when I'm done. I'll average about 3 to 4 commits per day to our main repository. I too use svn git, but not so I can crawl into my cave, but so I have a life rope that I can use to pull me out of a messy coding situation.
So, take a look at git svn, but please don't use the excuse that you have your own repository to hide away from the rest of your group. You can use the MS Git Provider (or the [SVN provider from AnkhSVN).