little conundrum

I have a little problem I am trying to solve. Tried a few things and got nowhere, so I thought I would ask here.

I have two directories one of which contains a tree of source code that was an original software package that I downloaded. The other contains the result of some unfinished - but quite substancial changes that I had made to that source code. Since this was some time ago, I don't have any records, but it is quite possible that I added and removed quite a few files.

I would like to make myself a git repository that contains at the start, an initial commit of the original downloaded source code, and a second commit on the top of that that contains the the current state of play after the changes I have made.

Since I don't actually have a list of the files, I thought I would establish these automatically by going into each directory and doing a cg-init. So I now have two disjoint repositories each with their source tree in it.

My next thought was to add a branch to one of them and then pull the resultant code over and merge it using cg-branch-add followed by a cg-update. But when I do that it complains that there is no common base.

I tried creating an empty directory and separately merging the two versions with it, so that I have a common parent, but whatever I do, I can't get one of those nice little gitk diagrams that has any linkage between the two versions of the source code.

Is there an approach I could take to achieve what I want?