Simplest righting line is a long rope tied to mast ball post, tucked into pocket on tramp. When tipped over, take rope out, and throw over top of hull.

But, since you talked about the mast being hard to step (heavy?), I assume it's an aluminum mast. The aluminum mast unis are almost impossible to right by yourself. You'll either need crew, help on the water, or a righting bar of some kind.

For righting lines & systems here are some illustrations :

iagrams in Murays Marine Catalog
http://www.murrays.com/archive/45-46.pdf

Gary's "SoloRight System"
http://www.geocities.com/hobiegary/soloright.html

and Rick White's "PowerRight" system
http://www.catsailor.com/power_righter.html

above two appear to be variants of the Isotope catamaran righting bar
http://www.intl-fiberglass.com/boats.html

I use a righting bar.