The new Linkage 3.5 is now available. It has connector settings to make a rotating input anchor oscillate between two angles (the first always being zero) with a settable starting position that also gets set automatically when pinning the mechanism.
There is also a new start position setting for linear actuator links. This also gets set automatically when the mechanism is pinned or can be set in the link properties.
Links to the download files are here: http://blog.rectorsquid.com/linkage-mechanism-designer-and-simulator/.
These are brand new little tested features so please report problems if you see them. I opted to release this instead of doing a beta test because no one uses the beta versions but me. Anyone interested in testing these features for me can just try them and see if anything goes wrong!