Keyboard Alteration

I have a need to use the Euro and Pound Sterling many times. I do this
by typing Alt and the appropriate number for each symbol. This can be a
bit of a nuisance. It seems that I read somewhere that these Alt+ codes
can be assigneed to specific keys on the keyboard. For example
assigning the code for the Euro symbol to the same key as the $ sign.
By typing Alt + Shift + 4 the Euro symbol would print. The same would
be done for the Pound Sterling symbol but it would be assigned to
another key.
Thanks for any and all help.