Rock Master Publications:
Sublime Climbs - A Guide to the best rock climbing venues in Victoria, Australia.By Kevin Lindorff, Josef Goding & Jarrod Hodgson. Over 700 climbs, 158 phototopos, 36 maps, and 380 pages covering the best of Mt Arapiles, Mt Buffalo and the Grampians $45.00
As a member of Friends of the Colo, no-one in the group will be able to offer any more to say other than the climbing site is just near the Lower Colo bridge (modern bigger concrete structure of the Putty Rd), on the opposite side of the river to where canoeists take out (after paddling down from the small timber bridge at Upper Colo).
An EPIRB wouldn't be mandatory - just get over to the Putty Rd and flag down a car, for I think the shop and caravan park is now closed. Yes, having an EPIRB is good, especially if there is only 2 in the group, but don't let not having an EPIRB constrain you. Mobile phone reception is minimal at best there.