CS Model question

Ok, heres the situation. I have a few player modles that I want to convert over to hostage models. SHould be simple right? wrong.

Ok I have a programe that makes adding these models a snap, but my problem is with the models themself. They show up fine, but with 1 small problem. They are half underground. I DLed a program called "Jed's Half-Life Model Viewer" and I can see where the problem is. Below you will see a picture of a hostage model that is fine

http://img192.exs.cx/img192/7011/a6is.gif

If you look you will see a grey box around the hostage. Thats the floor. The hostage is standing on the floor normally.

Now heres a picture of a hostage model thats not ok. If you look, that same grey box is now in the middle of the hostage. SO when in game, the hostage would be half underground, half normal.

http://img192.exs.cx/img192/9926/b8oa.gif

So my question is this. How can I edit the model so that it's standing on the floor? If you can help, PLEASE give alot of details. Kinds like a step by step cause I know nothing about models. If I need any programs, please include links if you can.

Thanks in advance