Oh I remember when I had to do this with Brooky! It is so hard
What shampoo are you using? Make sure you have a nice skin conditioner to use afterward if you are using something like Malaseb as while it is good for their skin, it can also take some moisture out (depending on what shampoo it is and the exact purpose you are using for). A good conditioner is for the skin, not for the hair of a dog. I really like PAW (Pure Animal Wellbeing) Sensitive Skin Conditioner (
http://www.paw4pets.com/products/sensitive-skin-conditioner) you have to leave it on for 5 minutes (oye, more waiting!) but it really helped her with her dandruff and great with medicated shampoo. Most doggie conditioners treat the fur to make it shine and smell nice, but always good to get one the treats the skin instead...especially if Bobby has dandruff. With Paw, you don't even have to worry about washing it all out. It is like lotion for the skin (and makes her fur nice as a bonus).
OKAY, now to your real question. Ha! What I did was put the shampoo on, then put her leash on so she couldnt run away and I used her dinner (or breakfast) to either to training, tricks, etc. or just hand feed it to her really slowly (kibble by kibble) so she stayed really focused and had something to do. I have done it outside and inside (could only do it outside in the summer as she got cold staying wet). But doing training, games ("sit", "stay", "come", "look", etc) or just really slowly hand feeding really makes the time go by every time! It is the only thing that really works. And don't worry if Bobby might cry a little the first time or two you keep this shampoo on him for that long, he is just getting bored (why food is a good distractor). Brooky is totally used to it now (because I still use the PAW conditioner and shampoos which stay on a little while anyway), so she just chills and eats her dinner
And hand feed vs. just putting the bowl down because it will take longer and you can draw it out.