Ok, a good way to make groups in Ms3d is to use the select faces tool. Check the "Ignore Backfacing" box and select your face one bit at a time. It's a serious pain, I know.
Once you have what you want to be your new group selected, press Ctrl + D, and rename it. (It will make a new group called Duplicate 01)
Texture Co-Ordinate editor allow's you to position where on the model your texture's are. Useful for logo's etc. Make sure the group is selected, then check the "Redraw" box. This will make the change with you, so you can see what each movement does. Select Any of the drop down menu's "Top, Bottom, Left, Right, Front, Back" to redraw the texture from that angle. It can be useful to avoid stretching textures. For windows, select the scale button and grab the box on the left, drag it around to make it bigger or smaller. Same with Move and Rotate.
I wish I could be more helpful, but it's mainly practise I'm afraid:(
EDIT: Misunderstood the question:P
Umm, try and zoom in and select the vertice's by hand, one at a time (Use Shift to select the next one etc) And if the group is already set, you can use the "Select" button under the groups to just select that one group.