2 deg,54 min x 1 deg,34mins is 174 arcmins x 94 arcmins
The field of view needed is that of your imaging device when applied to your scope. Obviously there are a wide range of FOVs we need to cover when you consider the various options folks have in terms of scopes, barlows, reducers, CCDs, webcams, DSLRs, SLRs etc. You don't have to be deadly accurate with setting the FOV values just err on the 'smaller' side and all that will happen is the mosaic will be slightly more overlapped.
For an imaging device at prime focus the FOV dimensions may be calculated as follows:
FOV (arcmins) = 3.438 * ChipDimension / FocalLength
Where ChipDimension and FocalLength are in mm. FocalLength should take into account magnification effect of any barlows/reducers in the imaging setup.
Note that the mosaic program assumes your imaging device's FOV is aligned in RA and DEC - so movement in RA moves stars horizontally across the image - adjusting the frame overlap should compensate for small errors in alignment.