Because I'm new to dialysis, I wanted to ensure what that I'm giving correct advice. I looked at the Bard Access Site:
http://www.bardaccess.com/
And from this site, as long as they are using the softer silicone catheters, ambulation can be done, though they do agree it is difficult. I do have two patients with temp femoral lines that due to vascular disease this is the only site for a catheter. They both do walk and in fact one works full-time. These are Perma-Caths so are made of softer material.
I know the temp accesses (I used to work in the ER where we used very stiff, very short, large bore central lines for emergent dialysis due to ingestion) are much more difficult to work with.