Hi !
I use ansi keyboards to type french and it works great. With US international settings in the OS (Win or Mac) you can get any accents : ', `, or ~ for example are dead keys for è you type ` then e.
if you want only ` then type ` then space.
It's a little more tricky as for example ` then p gives `p.
But I guess you can type any special characters spanish needs.
ñ, Ñ, or even á, é, í, ó, ú, ç
Hope I helped !