REmove the oil pan in the long run you will be much better off trying to do it with out removing the oil pan is just not the correct way to do it . Besides removing the oil pan is not that much more work and you are able to make sure nothing has fallen in after working on the front.
You can remove the timing cover without touching the oil pan yes, but you won't be able to get the bottom lip of the timing cover back on again during reassembly with the oil pan still there.
You have to at minimum loosen the oil pan bolts and drop the front of the pan down a few inches to allow the bottom timing cover lip to fall into place, making an oil change mandatory. If you go this far, you might as well just fully drop the pan all the way and renew your pan gasket. Use a one piece rubber Fel-Pro oil pan gasket. Forget the 3 piece or cork ones. Add some Permatex "The Right Stuff" to each corner of the gasket. Also ad a bead along the front and back of the gasket also. The gasket instructions will say to install the gasket dry, but using said sealant will not hurt anything. I have not had a drop of oil leak from my pan doing it this way in years.