EM5 in Oly housing with older strobes (Inon Z220, S&S YS 90DX)?

Looking to get back into UW photography, and the EM 5 in the Oly housing. I have two sets of older strobes, Sea & Sea YS 90 DX and Inon Z220s. My understanding is the Oly housing offers fiber optical triggering only. Can both the Sea & Seas and Inons be used with this housing, and are there specific cables I would need to get?

Starting from scratch but like to avoid having to buy all new gear...

I am using Inon Z220 with EM 5 without any issues. You need to ask for a "Nauticam to Inon optical fiber cable" and you are ready to go. Where I bought my stuff , there is also a cable for Sea&Sea too, so I believe you can use YS 90 too but I never had or used a Sea and Sea Strobe, so you better ask your dealer to make sure.

Don't know where you live but for reference check these :

http://www.onderwaterhuis.nl/optische-kabel-nauticam-naar-inon-26211.html

http://www.onderwaterhuis.nl/optische-kabel-nauticam-naar-sea-sea-26212.html

You will need the Sea and Sea to either Sea and Sea or INON fibre optic cables. The Nauticam to .... are for the DSLR housing range, the Sea and Sea to ... are for the compact and mirrorless ranges.