Diff merge question

I was wondering if the following functionality is present in the source 
gear client.

I want to do a diff between the current working copy of a file, and a 
specific revision (not the latest) of the same file in the vault.
This specific revision has not been labeled though.
So for example:
Do a diff between the local file and revision 5 of the same file which is 
checked in in the vault (the latest revision of the file
in the vault is revision 9).

Once I have the diff between the two files, I would then like to do a merge 
of the parts needed from the old revision.

Background behind this question is the following:
We removed some code in an earlier revision of a file, since this code 
wasn't to be used yet. However now
this code is going to be used and I have to merge this code back into the 
head revision.
The other programmer on the project however did not label this specific 
revision.

I could of course backup my working copy, then get the specific revision, 
then do the merge, and finally check the
working copy back in, but I was wondering if there is an easier way to do this.

With regards,

Arjan Jansen