Pictures. When in doubt, show pictures. Then again, I just shipped away my TV 1/48, so can't take pictures of that, so if that's what you're having problems with, then I don't have any specifically relevant material.
I think we all know the leg post involved (in red):
http://mcintosh.home.mindspring.com/valkyrie/leg_post2.JPG
But there seems to be some confusion about where it goes, with and without armor. The hole for without is in red; the hole for with is in green.
http://mcintosh.home.mindspring.com/valkyrie/arm_holes2.JPG
Then again, I often end up doing this when with armor, just resting the post in the indentation:
http://mcintosh.home.mindspring.com/valkyrie/common.jpg
Of course, if you get the arm packs on the wrong arms, you're going to have problems.
On the flip side of the arm packs you find the posts for joining the arms in blue, the post for joining the arm packs in yellow, the normal mounting point for the gun in green, and the mounting point for the gun on the arm packs in red. Notice the gun post is in the middle of the "space" for the gun handle. I had the same problem with the TV arm packs as the rest; the post is not properly centered.
http://mcintosh.home.mindspring.com/valkyrie/arm_gun2.JPG
And for gerwalk mode, the arms stick out just fine if you use the apparently endless ingenuity built into the 1/48 by Yamato (it totally amazes me how they designed this thing). You simply take the arms as a unit and push them more forward (towards the head) then you normally would. Note, you kind of have to hold the back end of the arms up some or the sholder hinges won't have the right angle to move:
http://mcintosh.home.mindspring.com/valkyrie/arms_free.jpg
I didn't put the pics into the thread due to the size (they're all 150-250KB).
Thanks,
Scott