Okay so assuming you aren't joking (and desperately trying not to make any firefighter jokes...).
It depends how you do it. The big thing is that it's just casual, if you look like youve gone to a lot of trouble it looks like you think she only likes you cos youre a firey , and youre trying to impress her .
Which would be lame.
Wheras , "how you wanna come by work and i'll show you round the fire engines" would be very cool, and probably secure the lay immediately (seriously , take her out that night , and fcuk her).
Erm , hoses , greased pole , um , appliances, er aqueous film forming foam....