There are a couple of way to go at this trans. A full manual valvebody converted to non-electronic, or a control box requiring a small amount of electrical work. I have found a couple of places doing conversions, and found an article on this conversion in an old ATRA magazine. the conversions were very expensive and doing it yourself would require a lot of work. An experienced builder would be challenged to do it. The one good conversion unit come from Australia and can be bought on e-bay
http://www.ebay.com/itm/Full-Manual-Valvebody-For-4L60E-Auto-Transmission-96-97-/350348889111 If your wanting to do this yourself here is a link to the ATRA article
http://jd.offroadtb.com/trans-docs/4l60e-manual-shift-conversion.pdf . Now the other option is a box built by Rossler transmission. This box plugs into the trans and uses the signal from your pressure manifold switch to choose the solenoid activation, and operates the pressure control solenoid at full line pressure. It also allows for a lock up provision. This box is a simple install requiring only a 3 wire hook up. I have built a couple of these transmissions using the Sonnex Smart Drum, the Sonnex Sun Shell, Alto clutch packs, wide Kevlar band, and 5 pinion gear sets. One is in a 3200lb Camaro Running 6.20s on the juice, while still seeing street duty.
Hope this helps,
Dan