AFAIK, there's no straight conversion for RF -> EU. Lava, though possible, is incredibly lossy.
What I did was get far enough using standard IC2 generators to make a macerator and a semi-fluid generator. Then, on the RF side, a carrot farm (garden cloches work well, or you can use phytogenic insolators from Thermal Expansion), an alchemical imbuer, and several fractionating stills. The process goes...
RF + regular phytogro -> carrots (Insolator, using a monoculture cycle specialization augment, also uses water)
Carrots -> biochaff (macerator)
Bio chaff -> biomass (alchemical imbuer, add water)
Biomass -> biogas (fractionating stills)
Biogas -> EU (semi-fluid generator)
This produces an insane amount of biogas, so I worked out the rough numbers for late-game EU generation using this method. This assumes all TE machines are resonant, with the maximum amount of auxiliary reception coils.
1 Insolator supports two macerators, each with 6 overclocker upgrades
Those macerators support 1 imbuer.
That supports 20 stills.
Those can fill, if my math is right, 1160 semi-fluid generators.
That'll produce an insane 18k EU/t for a measly 12k RF/t.
Need more RF and less EU (YES)? Feed some of the biogas and water into compression dynamos, and reduce the number of semi-fluids.
Of course, these numbers are old and may have been rebalanced. Also, the two-minute MFSU charge time comes at the cost of an absolutely massive amount of iron. Some tin, too, but mostly iron.