Hi - You can view the parish records, wills, and other records on film, so although it is quicker to research in the IOM it is quite possible to do so from overseas. We are also very lucky that so many indexes and transcribed wills for the IOM are freely available online (thanks to Brian Lawson who started this work in Canada from LDS films), and also to have the freely available records on Manx Notebook.
There are a number of publications of gravestone inscriptions etc available through the IOM FHS - well worth joining.

Sue