"i'm a little confused about seps. i'm self employed, and i already have a traditional ira. can i have a sep as well?"

Yes. You can also convert your traditional IRA to include SEP contributions.

"i would like to put away more than the $2000/yr that i put in my trad. ira, and have that savings be tax deferred as well. do i set up the sep and then deduct the amount on my schedule c? under pension contributions?"

Yes. Talk to your current IRA custodian and tell them you would like to set up a SEP. They will send you some forms to be filled out. As far as the SEP is concerned, only the employer can make contributions. You are your employer. Assuming you have no employees other than yourself, you don't have to also set up a SEP for anyone else.
Best wishes, Chris