Correlation of a ID Session

Hi,

Im trying to correlate an id session like this:

jhihbt45bt54bt54jh6%fgnkdjgndfjg5464t%kdsmfndkfg

% symbol its getting problems creating regular expression in a web_reg_save_param_ex. How can I set this regular Ex?

Could you please help me, it's very important and I'm a begginer.

Thanks a lot.