I've had my HLS5087 for quite some time now and have been trying to achieve 1:1 pixel mapping sucessfully without overscan since then. Using the help of Powerstip (a shareware utility) I have successfully managed to achieve this. I will outline the steps I used here so it may serve as a guide to others.
I found a guide to eliminate overscan on the Powerstrip website teh URL for which is :http://forums.entechtaiwan.net/viewtopic.php?t=2089
I'm sure that these steps can be used for a 720p TV as well but I'm only mentioning the 1080p TVs as I am familiar with them.
1. Connect the TV to the PC using a VGA cable, turn on the PC and TV and set the Source to PC.
2. Download and install the Powerstip utility from http://www.entechtaiwan.com/util/ps.shtm
3. Right-Click on the Powerstrip icon in the toolbar at the lower right hand corner of the screen and choose Display Profiles -> Configure
4. In the Display Profile window in the upper right hand quadrent change the resolution to 1920x1080 and make sure that the refresh rate is close to 60Hz.
5. Click Apply and the screen should be sized to the correct resolution supported by the TV.
6. There should be a black bar around the display area which can be removed by pressing the P.Size button on the remote.
7. In the P.Size menu that appears, it should say WIDE. Scrolling right to the last item in the menu should be the zoom icon. Press the Up direction key on this icon until the picture zooms in all the way and can zoom in no more. You will know when the screen has zoomed in fully because you will not be able to move any part of the screen using the other icons in the P.Size menu.
8. At this point the image has 1:1 pixel mapping but there are 40 or so pixels cut off from all sides. This is primarily because all projection TVs have some part of their screens that extend beyond the visible area.
9. To remove the overscan click on the Advanced Timing Options in the Display Profiles of Powerstrip.
10. Don't do any adjustment on this screen yet!
11. In the lower left hand quadrent of the screen click Custom resolutions
12. In the custom resolutions page click on the icon with the tooltip that says "Design a resolution-in-a-resolution" - This is the rightmost icon in the lower right hand quadrent above the Close and Add New Resolution button.
13. In the window that appears, carefully stretch it to fit the entire visible space on the screen. Once you're satisfied that the window covers the entire visible space of the screen, press OK on the window.
14. You will be back in the Custom Resolutions window with the Active Pixels in the upper right quadrent stating the new resolution that you picked.In my case it was 1880x1045.
15. Click on the Add New resolution button in the lower right quadrent and press OK on the resulting dialog.
16. Press Close -> Ok -> OK to get rid of the Display Options Window
17. Reboot your machine and go back into the Display Options Window in Powerstrip upon bootup.
18. In the upper right quadrent, slide the Resolution Slider to choose the custom resolution that you defined and click the Apply button.
19. The overscan should now be gone and only a few minor adjustments remain.
20. In the Display Options Window click on the Advanced Timing Options again.
21. in the Advanced Timing Options Window there are adjustment scales in the upper left quadrent(Position Size) which can be used to correctly fine tune and center the image o nthe screen.
22. Do not touch the Size buttons to increase or decrese the horizontal and vertical size - this will not give you good results. Instead either recenter the screen using the Position butons on the left or click and drag in the empty space between the two sets of Position and Size buttons to recenter the screen.
23. Once you are satisfied with the results hit the Ok button.
24. Back in the Dsiplay Options Window, click SaveAs in the lower part of the screen called Profiles and save the profile using a default or custom name.
25. You should now have a correctly sized image mapped to your TV at 1:1 pixel mapping. If the image is not centered, do not zoom in/out using the TV remote or powerstrip, instead go back and redo the resolution-in-a-resolution step to figure out the exact resolution for your tv.
Please feel free to add your input to the guide and correct any mistakes that I have made.