Here's the senate's judiciary committee page where you'll find contact info. A note in the senate calender said that remote testimony was available for this committee session, so if you'd like to testify but cannot make a physical appearance at the capital then go to this page, fill out the form and select the location closest to you from the drop down menu. It seems they have several locations around the state for a person to testify from. It's not perfect, but it'd save you driving into Denver from way out of town.
I am not positive, but the Colorado Channel may stream audio and/or video of the committee hearing. Try them at 1:30 p.m. MST.
SB15-086 (The UBC repeal [.pdf]) passed out of the senate judiciary committee (3-2) and was sent to the senate finance committee.
SB15-032 (The permitless carry bill [.pdf]) passed out of the senate and is waiting to be introduced in the house. (I discussed this bill a bit in this post here.)
Rocky Mountain Gun Owners' Billwatch page is a good way to keep up with the status of things in the state legislature, if you ain't hip to it already.
Update: 02-22-15 19:50 MST The hearing for SB15-175 has been postponed due to inclement weather.
Update: 03-07-15 14:25 MST The hearing for SB15-175 will be on Monday, March 9th at 1:30 p.m. MDT in room 271 of the capital building in Denver, Co.