|XP is just a number|
I am still running AS 5.24 so I haven't confronted the new procedures yet. On version 5.24, I have ppm and just used it to install the Tk package. That was easy to do.
With version 5.26, ppm disappears and the world changes!
The idea is that you create an account on the AS site. You then create a custom build with the packages that you need. AS will build the whole Perl installation for you - takes about 35 minutes. I looked at version 5.28 and Tk is already there. So you could just download and run the v5.28 .exe or the .msi file for that build. I would recommend if you upgrade that you uninstall your 5.26 first. In theory, just running the 5.28 msi on top of your 5.26 installation should "work". However, I would play safe and uninstall 5.26 first.
I looked at the 5.26 public build and it had Tkx, but not Tk. So I forked the public project and gave that branch a new name. then I added Tk 804.034 and committed the changes. That kicked off the build process. Its running right now, AS says they will email when my .exe and .msi files are ready for my custom named branch - will appear in my account for download.
So in theory, the custom 5.26 build that AS is making for me will include Tk. I had to manually install one package that was failing in the 5.24 build (I needed a dev version). So I am not inclined right now to upgrade to 5.26 or 5.28 and have to potentially confront an old problem once again.
So I am sorry that I can not give you a completely tested answer. However, from what I can tell, this new AS build procedure is working (its still running as we speak).
In the past, there were a set of tools where I could make a config file with all the modules that I had installed on my dev system. Then I give you this config file which you then apply to your base Perl installation and in theory "bingo" you have cloned my AS setup with all the modules that I have. I found some hiccups with that idea in practice. This new procedure is designed among other things to fix those problems. Also under the AS EULA, I couldn't just make a .zip file of my Perl file structure and give it to you. However, my understanding is that for a build that is done this way, I can re-distribute the AS built .msi file.
I didn't write down all the details of how to create an account, etc. I just clicked around and fumbled through the above procedure. I think this has a lot of promise. Give it a go and tell us how it works for you. In theory, you should get a working version out of this.
Update: I guess if we are getting nitpicky about this, I haven't told you how to install Tk manually - this is an xy
problem. I am telling you do to y instead of x which you asked for.