Q:

Tachanun with No Seats

Many times I'm in Shul and don't have a place to sit for Tachanun. What's proper procedure in such cases?

A:

If one leans against something to the point that if it were removed he would fall it is considered as if he were sitting. Will give you source when I get a moment.

A:

Lean your head on your arm while standing.  At the end of the first paragraph (usually the transition from seated-leaning to seated-normal), stop leaning; at the start of the next paragraph (usually the transition from seated-normal to standing), just stay standing.  
Sitting is the preferred position for head-leaning, but not required for it.

